Infinitely variable seat height adjustment with top lift. New designer backrest (semi-open/closed) with breathable elastane mesh cover, height and tilt adjustable via ratchet mechanism. Comfortable intervertebral disc seat for optimum support in the pelvic area. Synchronised mechanism for synchronous adjustment of seat and backrest tilt, spring force individually adjustable to body weight, continuously lockable. Black polyamide base or optionally with chrome-plated steel base at an extra charge, equipped with load-dependent braked double safety castors for carpeted floors.