The seat and backrest follow the movements of the person sitting in a synchronised manner and at the correct angle. Infinite, immediately noticeable adjustment of the constant backrest counterpressure in all working positions (for body weights of approximately 40-125 kg). Patented automatic weight compensation for a permanent upright seated posture (Patent no. EP 06 35 228 B1). Synchronised movement can be locked in 4 positions (SD I). Standard: dual position seat-tilt adjustment (0°/-6°) for TakeOver, Zeta operator, @Just. Option: infinite locking of synchronised movement (SD II). Option: Auto-Glide-System (automatic seat-depth regulation (6,5 cm) during the synchronised movement process, in addition can be individually locked in 7 positions).