The 329 Foot Operated Hydraulic Pump Stool with Ergonomic Backrest is premier line of foot-operated hydraulic seating. The smooth foot-operated hydraulic pump provides up and down adjustments of the seat height from 20.5”-28” (52-71 cm) without ever getting off the stool. This adjustment helps provide sterile and precise positioning to your most comfortable working position. Single wheel hard rubber casters make it easy to maneuver quietly over all types of surfaces without damaging or marring the floor. Treat yourself to a soft and supportive seat with premium line of seating.