# Onyx High Back Ergonomic Posture Office Chair

> High back ergonomic posture office chair with a triple lever mechanism giving independent seat and back angle adjustment, a ratchet backrest. Optional headrest, 22 upholstery colours and black back…

- URL: https://deskwell.co.uk/onyx-high-back-ergonomic-posture-office-chair-with-adjustable-arms
- Type: Product
- Last updated: 2026-09-11
- Price: £386.00 ex. VAT to £518.00 ex. VAT, by choice
- Availability: In stock (3807 across 84 combinations)
- 3D model: Yes - 84 of 84 variations
- Photographs: 7
- Supplier: Dynamic Office Solutions

## Description

High back ergonomic posture office chair with a triple lever mechanism giving independent seat and back angle adjustment, a ratchet backrest, pump up lumbar support and seat slide. Contoured foam seat and back, height adjustable arms, brushed aluminium base. Rated for 24 hour use, 135kg capacity, optional headrest, 22 upholstery choices.

#### Three levers, every angle covered

Most chairs give you one lever and call it ergonomic. The Onyx's triple lever multi-function mechanism adjusts the seat and backrest independently: tilt the seat forward by anything from 1 to 15 degrees, set the back angle anywhere across a 20 degree range, and let the permanent contact backrest stay with you as you move. The backrest also ratchets for height so support lines up with your spine, and tilt tension adjustment tunes the feel to the person sitting in it. It is asynchronous adjustment in the proper sense, with each part of the chair set to suit you rather than the average of everyone.

#### Contoured comfort, pumped to fit

The seat and backrest are contoured foam, shaped to support rather than flatten over time, with a pump up lumbar support you inflate until your lower back is held just right. The seat slides between 46cm and 51cm deep to suit longer or shorter legs, gas height adjustment runs from 49.5cm to 57cm, and the height adjustable arms move from 63.5cm to 73.5cm, coming off entirely if you prefer to sit armless. Add the optional headrest and your neck is looked after too.

#### Finished your way

Choose from 22 upholstery options: black fabric or black leather from stock, or 20 bespoke colourways across collections including Rivet and Quest. Keep the backrest black against a coloured seat, or have it upholstered to match. The foam and fabric are UK Crib 5 specification, and the brushed aluminium five star base finishes it off properly.

#### Right for your business

The Onyx suits anyone furnishing desks where posture actually matters: busy offices, 24 hour operations and home workers replacing a chair that never quite fitted. One clear price, full specifications on the page, and no sales calls required.

Seat

- **Gas seat height adjustment, 49.5cm to 57cm.** A tall range that suits standard and higher desks alike, keeping feet flat and thighs level.
- **Seat slide with a 46cm to 51cm depth range.** Slide the seat forwards or back so legs get full support without pressure behind the knees.
- **Seat angle adjustment, 1 to 15 degrees.** Tip the seat to open the hip angle and take pressure off the lower back.
- **44cm wide contoured foam seat.** Shaped support that keeps its form through long working days.

Backrest and posture support

- **Ratchet height adjustable high back, 43cm wide.** Clicks up and down so support sits exactly where your spine needs it.
- **Back angle adjustment, 1 to 20 degrees.** Set the backrest angle independently of the seat for a genuinely tailored position.
- **Permanent contact backrest.** Stays in touch with your back as you move, supporting rather than waiting for you to lean back.
- **Pump up lumbar support.** Inflate the lower back support until the firmness is exactly right for you.
- **Optional headrest.** Choose the chair with or without neck support for long stints at the desk.

Armrests and base

- **Height adjustable arms, 63.5cm to 73.5cm.** Keep elbows supported at desk height and shoulders relaxed.
- **Removable arms.** Take them off entirely for armless sitting or to pull fully under the desk.
- **Brushed aluminium five star base.** A smart, sturdy foundation that looks as good as it rolls.

Size, capacity and usage

- **65cm wide, 67cm deep footprint.** Full-size posture support that still fits a normal workstation.
- **135kg maximum weight capacity.** A heavy duty rating, comfortably above the standard office chair.
- **Recommended for 24 hour use.** Built and rated for continuous sitting, not just the working day.
- **UK Crib 5 foam and fabric.** Contract-grade materials specification throughout the upholstery.

Guarantee

- **5 year guarantee on mechanical components, 2 years on fabric and foam.** Long cover on the moving parts, so the chair is still doing its job years from now.

More chairs built around good posture in our [ergonomic office chairs](https://deskwell.co.uk/shop/categories/ergonomic-office-chairs) range.

## Variations

| Choice | SKU | Price | Stock | 3D model |
| --- | --- | --- | --- | --- |
| With Headrest, Black Bonded Leather, Black Back | OP000098 | £407.00 ex. VAT | 100 | Yes |
| With Headrest, Black, Black Back | OP000094 | £407.00 ex. VAT | 44 | Yes |
| With Headrest, Bergamot Cherry, Black Back | KCUP0417 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Bergamot Cherry, Matching Back | KCUP0433 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Ginseng Chilli, Black Back | KCUP0422 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Ginseng Chilli, Matching Back | KCUP0438 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Maringa Teal, Black Back | KCUP0423 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Maringa Teal, Matching Back | KCUP0439 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Myrrh Green, Black Back | KCUP0418 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Myrrh Green, Matching Back | KCUP0434 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Crab, Black Back | KCUP4041 | £448.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Crab, Matching Back | KCUP4029 | £518.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Kelp, Black Back | KCUP4042 | £448.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Kelp, Matching Back | KCUP4030 | £518.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Limpet, Black Back | KCUP4043 | £448.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Limpet, Matching Back | KCUP4031 | £518.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Mussel, Black Back | KCUP4044 | £448.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Mussel, Matching Back | KCUP4032 | £518.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Salt, Black Back | KCUP4045 | £448.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Salt, Matching Back | KCUP4033 | £518.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Shell, Black Back | KCUP4046 | £448.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Shell, Matching Back | KCUP4034 | £518.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Shrimp, Black Back | KCUP4047 | £448.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Shrimp, Matching Back | KCUP4035 | £518.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Whelk, Black Back | KCUP4048 | £448.00 ex. VAT | 44 | Yes |
| With Headrest, Quest Whelk, Matching Back | KCUP4036 | £518.00 ex. VAT | 44 | Yes |
| With Headrest, Rivet Tensile, Black Back | KCUP4040 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Rivet Tensile, Matching Back | KCUP4028 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Rivet Forge, Black Back | KCUP4037 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Rivet Forge, Matching Back | KCUP4025 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Rivet Fuse, Black Back | KCUP4038 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Rivet Fuse, Matching Back | KCUP4026 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Rivet Quench, Black Back | KCUP4039 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Rivet Quench, Matching Back | KCUP4027 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Senna Yellow, Black Back | KCUP0421 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Senna Yellow, Matching Back | KCUP0437 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Stevia Blue, Black Back | KCUP0419 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Stevia Blue, Matching Back | KCUP0435 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Tabasco Orange, Black Back | KCUP0420 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Tabasco Orange, Matching Back | KCUP0436 | £492.00 ex. VAT | 44 | Yes |
| With Headrest, Tansy Purple, Black Back | KCUP0424 | £439.00 ex. VAT | 44 | Yes |
| With Headrest, Tansy Purple, Matching Back | KCUP0440 | £492.00 ex. VAT | 44 | Yes |
| Without Headrest, Black Bonded Leather, Black Back | OP000099 | £386.00 ex. VAT | 17 | Yes |
| Without Headrest, Black, Black Back | OP000095 | £386.00 ex. VAT | 46 | Yes |
| Without Headrest, Bergamot Cherry, Black Back | KCUP0425 | £418.00 ex. VAT | 46 | Yes |
| Without Headrest, Bergamot Cherry, Matching Back | KCUP0441 | £471.00 ex. VAT | 46 | Yes |
| Without Headrest, Ginseng Chilli, Black Back | KCUP0430 | £418.00 ex. VAT | 46 | Yes |
| Without Headrest, Ginseng Chilli, Matching Back | KCUP0446 | £471.00 ex. VAT | 46 | Yes |
| Without Headrest, Maringa Teal, Black Back | KCUP0431 | £418.00 ex. VAT | 46 | Yes |
| Without Headrest, Maringa Teal, Matching Back | KCUP0447 | £471.00 ex. VAT | 46 | Yes |

34 further combinations are available on the page itself.

## Specification

| Attribute | Value |
| --- | --- |
| Overall Width | 65cm |
| Seat Width | 44cm |
| Back Type | High |
| Arms Included | Yes |
| Seat Slide | Yes |
| Mechanical Components | 5 Years |
| Overall Depth | 67cm |
| Seat Depth | 46-51cm |
| Back Width | 43cm |
| Arm Type | Height Adjustable |
| Seat Angle Adjustment | Yes |
| Fabric & Foam | 2 Years |
| Seat Height | 49.5-57cm |
| Arms Removable | Yes |
| Gas Height Adjustment | Yes |
| Height Adjustable Back | Yes |
| Arm Width | 45cm |
| Tilt Tension Adjustment | Yes |
| Maximum Weight Capacity | 135kg |
| Permanent Contact Backrest | Yes |
| Arm Height | 63.5-73.5cm |
| Recommended Usage | 24 hours |
| Independent Seat & Back | Yes |
| Integral Lumbar Support | Yes |
| Adjustable Lumbar Support | Yes |

## Where it sits

- [Ergonomic Office Chairs](https://deskwell.co.uk/shop/categories/ergonomic-office-chairs)
- [Call Centre Furniture](https://deskwell.co.uk/shop/collections/call-centre-furniture)
- [Office Chairs for Back Pain](https://deskwell.co.uk/shop/collections/office-chairs-for-back-pain)

## Questions and answers

#### How big is it?

There are two heights (102cm to 114cm or 118cm to 143cm). Every one is 65cm wide and 67cm deep.

#### What upholstery colours are there?

There are 22: Black Bonded Leather, Black, Bergamot Cherry, Ginseng Chilli, Maringa Teal, Myrrh Green, Quest Crab, Quest Kelp, Quest Limpet, Quest Mussel, and 12 more. The swatch beside each name on the product page is a photograph of the actual cloth, so what you see is what arrives.

#### What is the weight limit?

It is rated to 135kg. Sitting time is cleared for 24 hour use, so it stands up to shift work and control rooms rather than one working day.

#### How high is the seat?

The seat sits at 49.5cm to 57cm. It is on a gas lift, set with the lever under the seat. A desk of around 72cm to 74cm suits that range, which is what nearly every office desk is built to. The seat itself is 44cm wide and 46cm to 51cm deep.

#### Does it have arms?

Yes, arms are included. Where fitted, they adjust for height, and they come off altogether if you would rather do without. Arm height is 63.5cm to 73.5cm from the floor.

#### Is there proper back support?

Yes, and it adjusts. You can set the support where your own lower back curves rather than where the average back is assumed to curve, which is the difference between a chair that helps and one that nags.

#### Is there a headrest?

That is a choice on this chair: With Headrest or Without Headrest. It adjusts for height.

#### How does the chair adjust?

Seven things: the seat height is on a gas lift, a tension dial sets how hard you have to push to recline, the seat and back angles are set independently of each other, the backrest follows your spine instead of staying put, the backrest slides up and down to meet your back, the seat slides forward and back to set the depth, and the seat angle tilts separately. All of it is worked from levers under the seat, and the instructions in the box say which lever does what.

#### Does it come assembled?

It arrives flat-packed as standard, with the instructions and fittings in the box. If you would rather not build it, there are two other choices at checkout. Pre-assembled delivery is £15 an item and it turns up built, ready for you to point at the spot. Installation is £17.95 an item and the crew build it and put it where it is going.

#### How long does delivery take?

Standard delivery is free and usually lands inside a week. If you are in a hurry, express is £4.95 an item and gets it to you within two working days when you order before 5pm. Some of the options on this page are made to order rather than stocked, and those take 10 to 15 working days. The date it will arrive by is on the page and again at checkout before you pay, counted in working days with weekends and bank holidays already taken out.

#### What warranty does it come with?

It carries the manufacturer's warranty. That covers the mechanism for five years and the fabric and foam for two years. If something fails inside the warranty, report it from your order page and we deal with the manufacturer for you.

#### Can I change my mind after ordering?

This one is upholstered to order in the fabric you choose, so it is built for you and cannot be resold. That means no cancellation once we have acknowledged the order, and no return simply because you have changed your mind. Take a moment over the options before you check out. If it arrives damaged or faulty that is a different matter and your rights are untouched: report it from your order page with photographs and we will put it right.

#### What makes a chair ergonomic?

Adjustment that meets the body rather than the average of all bodies. In practice: seat height and depth, independent seat and back angles, lumbar support that moves to where your back actually curves, arms that adjust in more than one direction, and a tilt tension you can set to your weight. A chair with none of that is not ergonomic because the label says so.

#### Are they worth the money?

For anyone sitting most of the day, usually yes. These run £112 to £395, and the difference over a task chair buys adjustment and better foam rather than a nicer photograph. For a chair used a few hours a week, it is money better spent elsewhere.

#### Will one fix my back?

We are not going to promise that, and nobody honest will. A well-adjusted chair with proper lumbar support removes one common cause of discomfort, and it helps considerably. It does not treat an existing condition, and if there is a medical reason behind the problem, an assessment will get you further than a product page.

#### Does it need setting up?

Yes, and it is the step people skip. All that adjustment is worth nothing left at the factory setting. Ten minutes with the levers when it arrives is the difference between an expensive chair and a comfortable one.

#### Are any of these rated for shift work?

Some are rated for twenty-four hour use, which is what you want for a control room or a desk that never empties. The rating is on each page, and the heavy duty category collects the rest.

#### Do you offer installation?

Yes, on everything here. The crew deliver it, build it, put it where you want it and take the packaging away. It starts at £17.95 an item and the exact price is on each product page. Installs usually happen within about 10 working days, and the team agree the day with you rather than simply turning up.

#### Can I see it in 3D?

Twelve of the 13 products in this category have a 3D model on the page rather than only photographs. The viewer spins the actual model, and changing a colour or a size on the page changes the model with it, which is worth doing before committing a whole room to a finish.

#### Can you quote for a whole office?

Yes. For twenty items or more, or anything with a complication like a mezzanine or a lift that argues back, we plan the job and give you one quote covering the goods, delivery and installation. Ring 0208 138 0512 or email hi@deskwell.co.uk with a rough list or a floor plan.

#### How do I choose an office chair?

Start with how long it is sat in. A chair rated for eight hours is built differently from one rated for two, and the rating is on every product page. Then the person: weight rating, back height and whether the arms need to adjust. Then the room. There are 218 chairs here from £3, so the filters are usually quicker than the scrolling.

#### What does contract seating mean?

That the chair is built to be sat in by different people all day, every day, rather than by one person in the evening. It shows up in the foam, the mechanism and the fabric rub test rather than in the photograph, and it is the reason an office chair costs more than a similar-looking one from a domestic shop.

#### What do the hour ratings mean?

The number of hours a day the maker builds the chair to take. Eight hours is a full-time desk chair. Two to six hours covers visitor, meeting and breakout seating. Twenty-four hours means shift work: control rooms, dispatch desks, anywhere the chair never gets to cool down. Ratings across this category run from two hours to twenty-four.

#### Is there a weight limit?

Every chair has one and it is on the page. Across this category they run from 100kg up to 1200kg. If somebody is near the limit of an ordinary chair, the heavy duty range is built for it rather than being simply a bigger seat.

#### Do I have to be a business to buy from you?

Yes. Checkout asks you to confirm that you are buying for your business, trade or profession rather than as a consumer, and it asks for a company name. That is why prices are shown without VAT and why the terms read the way they do. Sole traders and home-based businesses count, and so does an employer buying a desk for somebody working from home.

#### Do your prices include VAT?

No. Every price on the site is shown excluding VAT, because most of our customers reclaim it. VAT is added at checkout and the total you actually pay is on screen before you confirm anything. A VAT invoice follows once the order is complete. Our VAT number is GB 525 3667 81.

#### How do I pay?

Payment is due in full when you order, and the methods available to you are shown at checkout. If you pay by bank transfer, your order is not accepted and the lead time does not start until cleared funds reach our account, so it is worth sending it the same day.

#### Can I pay on account, or on 30 day terms?

No. We take payment before the order goes to the supplier, so there is no credit account to open and no application to fill in. It keeps our prices where they are, and it means nothing is waiting on a credit check while you are waiting for furniture.

#### Can I put a purchase order number on the order?

Yes. There is a Purchase Order Number box at checkout, and what you type there carries through to the paperwork so your accounts team can match it up.

#### Do I need an account to order?

No, you can check out as a guest. You will still be able to see the order afterwards: go to Track Order, give the order number and the delivery postcode, and you get the same order page an account holder sees, with the same buttons for returns, cancellations and damage reports. Making an account simply saves typing the address again next time.

#### How much is delivery?

Standard delivery is free on everything, whatever the size of the order. The paid options are upgrades on top of that: express, pre-assembled and installation, each priced per item and shown on the product page before you add anything to the basket. Where an option is not shown on a product, it is not available for that product.

#### Do you deliver everywhere in the UK?

We deliver across mainland UK. A number of postcodes sit outside the standard service: Northern Ireland, the Scottish Highlands and Islands, the Isle of Man, the Channel Islands, the Isle of Wight and the Isles of Scilly. We can usually still get furniture to those places, but it has to be quoted rather than booked from the site, so ring 0208 138 0512 or email hi@deskwell.co.uk before you order.

#### Will the delivery crew bring it inside?

Standard delivery is to the door, flat-packed. If you want it carried in and built, choose pre-assembled delivery or installation on the product page. Whichever you pick, the crew ring roughly 30 to 60 minutes before they arrive, so you are not waiting by the window all morning.

#### Can I change my delivery date?

Yes, but not on the day. Our courier partner Furdeco plan their routes in advance, so the three hour slot cannot be moved once the van is out. To rebook for another day, ring Furdeco on 0121 285 5255 with your tracking number and pick a time that suits you. Larger deliveries and installations get a call from our logistics team first anyway, so the day is agreed with you rather than sprung on you.

#### Can I tell the driver how to find us?

Yes, and it is worth doing. There is a box on the delivery step at checkout, 500 characters, for anything the crew needs to know: where a lorry can park, which floor you are on and whether there is a lift, loading bay hours, a gate code, a one-way system the satnav has never heard of, and who to ask for. It travels with the order rather than sitting in a note at our end. It cannot be edited once the order is placed, so if something changes, ring 0208 138 0512 with your order number.

#### What happens if I miss the delivery?

The courier team will contact you to arrange another date, or you can ring Furdeco on 0121 285 5255 with your tracking number and rebook it yourself. Worth avoiding if you can: a failed delivery costs from £10 an item, plus storage if the order has to go back to a warehouse. A gate code in the delivery instructions box costs nothing.

#### Can you take the old furniture away?

Yes, we run a removal and recycling service, quoted per job. It has to be booked before delivery day, because the crew can only take away what they have been booked and equipped to take. Tell us what is going when you order and the swap happens in one visit rather than two.

#### Can I return something?

Tell us within 14 days of receiving it and we will look at it. Go to your order page, either signed in or through Track Order with the order number and delivery postcode, and raise the return there. The goods have to be unused and back in their original boxes, or packed well enough to survive the journey. If you send them back yourself there is no handling charge at all and carriage is at your cost. If you would rather we collected, we may charge up to £35 an item, and we tell you the figure before we collect. Anything you paid for on top, like express delivery or installation, is not refunded, because those services were already carried out.

#### Can I cancel an order?

Ask as soon as you can, from your order page. Before anything is dispatched we can often cancel it, though where costs have already been incurred with the supplier we may deduct those before refunding the balance. Once something has been dispatched it becomes a return rather than a cancellation. Made-to-order items cannot be cancelled at all once we have acknowledged them.

#### Something arrived damaged. What do I do?

Tell the delivery crew at the door. They note it down and photograph it, and that record is what settles the claim with the carrier later. If you turn the delivery away because of the damage, the crew take the goods with them and we arrange a replacement. If you only spot it after they have gone, open your order, press Report a problem and send photographs, up to six on one report. Do it within five days: carriers stop entertaining a claim once a delivery is more than a few days old. A damage report is counted separately from a return, so a breakage does not use up your 14 days.

#### How do I track my order?

A confirmation email lands as soon as you order, and the moment it is on its way you get a dispatch email with a full tracking link. You can also go to Track Order at any time with your order number and the delivery postcode. Your order number starts with DW.

#### Is everything on the site actually in stock?

Anything out of stock is hidden from the listings, so if you can see it and add it to a basket, we can get it. The exception is made-to-order items, which are not held in stock by design: they are built for you after you order, and their pages say so.

#### How do I get hold of a person?

Ring 0208 138 0512, email hi@deskwell.co.uk, or use the live chat on the site. If it is about an existing order, have the order number to hand and it will be quicker.

#### Who are Deskwell?

Deskwell Limited, company number 17332661, VAT number GB 525 3667 81, registered at 22 Blackwall Basin Moorings, 1 Myers Walk, Canary Wharf, London E14 5GT. We sell contract office furniture to businesses of any size, from a single home-office desk to a floor of workstations.