Our 509 Series hygienic features a foot-ring height adjusted pneumatic cylinder with a polished aluminum base. 3-1/2 inch foam padding, 15 inch seat and sealed seams provide comfort and durability. Please note the backrest option, shown on the 509 series, is available on all clinic stools. Seat height can be adjusted from 21 to 28 inches by a foot-ring, pneumatic cylinder Mounts on a 25 inch polished aluminum pedestal for unmatched stability Large seat for superior comfort Backrest edges are protected from cuts, scrapes, and general wear with a vinyl bumper