This product is a physio approved ergonomic office chair with multiple features for personalisation of the chair to best suit your shape and weight. Features include a moulded foam back, inflatable lumbar support, seat slide for seat depth adjustment and a height adjustable ratchet back. The asynchro mechanism allows you to independently fix or free float the backrest and the angle of the seat including forward seat tilt. The torsion control knob is for adjustment of the tilt tension to match body weight.
This is a great chair which you can adjust in so many different ways to make sure it's completely comfortable for you. It's also really easy to put together. I'm really pleased with mine.. Paula. Horley, GB. Sun Sep 20 2020