RH Extend 100 (medium synchro back) Ergonomic Office Chair

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Lead Time: 6 Weeks
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Now £789.60 £658.00
Now £789.60 £658.00
Group Created with Sketch. item product
Lead Time: 6 Weeks
Delivery and returns -
find out more
Customize RH Extend 100 (medium synchro back) Ergonomic Office Chair
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Reasons to Buy

The RH Extend chairs are user friendly, durable and ergonomic

They are easy to use, with all controls conveniently located on the right while all adjustable parts of the chair are clearly marked.

The RH Extend 100 has an adjustable tilt mechanism which allows the chair to follow the user's movement without muscular effort, providing support and encouraging the correct sitting position.

The 100 version of the RH Extend has a low back and uses a synchro mechanism so the backrest and seat angle move simultaneously when moving. The chair maintains its basic settings regardless of forward and backward movement or lock and release of the tilt mechanism. Both the RH 100 (medium back height) and RH 120 (high back height) have this function.

  • Lower back ergonomic chair
  • Adjustable tilt mechanism
  • Made from 100% recyclable materials
  • Follows RH’s 2PP chair philosophy of movement
  • Durable base - the RH Extend's base is made of aluminium with black scuff caps for protection
  • Optional adjustable armrests, these can be adjusted vertically, horizontally and rotated to provide full flexibility in supporting different arm lengths
  • Optional adjustable headrest
  • Easily accessible controls
  • The Waterfall edge seat reduces pressure on the underside of the thighs to help circulation. The shape keeps the user in the middle of the seat even when pointed correctly forward at the right angle. The seat can be replaced if damaged
  • Equipped with Twedts cushion providing quality support for the whole upper body. The shape encourages movement and height can be adjusted with a push of a button
  • Soft floor castors for surfaces such as carpet, designed to minimise damage to floor. Hard floor castors for surfaces such as laminate and concrete are restricted in movement once seated to stop the chair rolling away. Please specify hard floor castors when placing your order
  • The RH Extend is a great choice for modern and ever changing work environments with multiple users of the same chair. Perfect for hot-desking!
Fabric Colours
  • Available in black, navy and royal blue
  • 8S Class A armrests - Adjustable in height and width. Rotating. Armrest height above seat 215–295 mm
  • 8E Class A armrests - Black - Black Frame. Adjustable in height, depth and width. Armrest height above seat 215-295 mm
  • 8R3D Relax armrest (single arm) - Adjustable height, depth and sideways position
  • RH extend headrest
XL Seat
  • XL Seat - 485(w) x 515(d) mm - suitable for larger users
Gas Stem
  • Standard height 4Q gas stem (400–510 mm)
  • High gas stem B (480-610 mm) - suitable for taller users
  • Base in Grey Lacquered Aluminium (as standard)
  • Base in Black Aluminium (5X)
  • Base in Polished Aluminium (5X)
  • Castors for carpeted floors (as standard)
  • Castors for hard floors
Coat Hanger
  • Coat Hanger (requires headrest)
CMHR Foam Seat
  • CMHR (Combustion Modified High Resilient) foam is used when the strictest fire code standards are required, such as in hotel lobbies, hospitals, schools, mass transit (airplanes, buses). The foam has a high density which helps it last a long time. Fire retardant chemicals in the foam give the texture a grainy feel
Seat width:
465 mm
Seat depth:
475 mm
Seat height:
410-510 mm
Seat sliding range:
60 mm
Backrest width:
435 mm
Backrest height:
510 mm
Maximum user weight:
133 kg (21 stone)
28 kg
10 years, based on 8 hour use
Supporting Documentation
Product Videos
Q: How do I adjust the back angle of my RH Extend 100 medium back chair?

There is a row of 3 buttons on the right hand side of your Extend 100. Lift the middle button to adjust the backrest angle. Release the button to lock in place. The angle should be set so that your back makes contact with the backrest.

Q: My gas stem seems a little stiff – is this normal?

Sometimes, over time, the gas stem can become a little stiff when trying to adjust the height. A quick and easy fix for this is using WD-40 or Vaseline. Apply a light layer of grease to the gas stem, then try adjusting the gas stem 3-4 times. The gas stem should now adjust easily.

Q: Can my seat slide forward?

There is a row of 3 buttons on the right hand side of your Extend 100. Lift the button furthest back on the right hand side. About four fingers width between the front edge of the seat and the hollow of the knee provides good blood circulation.

Q: How do I adjust the height of my headrest?

Simply move the headrest up/down to adjust to the correct height for you. If you want to adjust the depth of the headrest, turn the knob on the side of the headrest clockwise or anticlockwise, depending on what is comfortable for you.

Q: How do I stop the rocking motion of my RH Extend 100 medium back chair?

There is a tilt lock on the right hand side of your Extend 100, at the back. Turn the handle clockwise to lock your Extend 100. To unlock, simply turn the handle anticlockwise.

If you want to adjust the tension of the tilt motion, use the front handle under the right hand side of your seat. Turn anticlockwise for firmer tension and clockwise to loosen the tension.

Q: We have hot-desking and I want to adjust the backrest height – how do I do this?

There are 2 buttons on the right hand side of your backrest. Press the bottom button to adjust the backrest into the desired height. Lock in position by releasing the button.

Q: My seat has become worn over time – can I just swap a new one for the old one?

Yes, swapping the seat pad is simple. Once you receive your new seat pad, pull off the old worn seat pad. You will notice there are holes underneath around the edge of the seat pad. Simply align these to the seat shell, then push down on the edges to secure the seat pad into place.

Still having problems?

Please give our customer services team a call on +44 (0) 345 345 0010.

Contact us about your seating project

Need more than one chair? However big or small your project is, we have a dedicated service to support you. Not only will you get expert advice, trials, delivery and set-up, but you’ll also benefit from great discounts on bulk orders.

To request a no-obligation quote, or to discuss your requirements further, please fill out our contact form and we will get back to you as soon as possible.