Ergonomic features in a rugged contemporary design, the Alvin Premo Black Drafting Ergonomic Chair is the ultimate in seating comfort at a reasonable price. Backrest provides solid orthopedic spine support and full-size upholstered seat is contoured for added comfort. Features include pneumatic height control, polypropylene seat and back shells, a height and depth adjustable backrest with heavy-duty spring tension angle control, dual-wheel casters and a 25" diameter reinforced nylon base. Seat cushion is 19" w x 17" d x 3" thick. Backrest is 16" w x 14" h x 2-1/2" thick. Drafting model includes CK49 height extension kit and adjusts from 24" to 29".