CH444 Premo Drafting Chairs. Incorporating quality ergonomic features in a rugged contemporary design, the Premo 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 steel 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. Includes CK49 height extension kit that adjusts from 24" to 29".Or without kit can be used as a lower office chair.