Safco Products TaskMaster Economy Industrial Chair (Model 5117) Overall height of 17" to 35" 8" of pneumatic lift and an additional 10" with our Wave Tube Extension Seat has a 2-1/2" deep cushion Ergo knob controls for 3" backrest depth and 3" backrest height adjustment 5-leg, 26" dia. tubular steel base with 2-1/2" high-impact nylon glides