Alvin CH728-45DH Argentum Mesh Back Drafting Chair, Contemporary Look, Ergonomic Design, Heigh Adjustable Backrest with tightly stretched silver mesh backing and ergonomically contoured design, Pneumatic height control, Multiple controls for adjusting back rest tilt independently or in synchronization with seat tilt, Dual-wheel casters, 26in diameter polished aluminum base, Backrest is w19,5in x h19.5in, Seat cushion with long-lasting molded foam is w19.5in x d18in x 3in thick, Includes CH728-45 Chair and CK49 height extension kit to adjusts from 24.5in to 28.5in height, Ship Weight 45 lbs, Ship Dimensions 31 x 24 x 14 in, UPC 088354802426.