Deeply contoured backrest provides support and comfort. Ergonomic shape helps minimize back strain and fatigue. High-density foam retains its shape. Machine-washable 100% polyester cover. Elastic strap adjusts to fit any chair. Back Support Type: Chair; Material(s): High-Density Foam; Width: 13 in; Depth: 4 1/2 in. Manufacturer's limited lifetime warranty. Includes one backrest.