The BT-ATB is a rough terrain sport wheelchair designed for use by individuals with mobility disabilities or spinal cord injury. FRAME (LxW): 16 x 16 inches 6061 T6 aluminum powder coat frame with 1.5-inch tubing. SEAT (WxD): 16, 17 or 18 x 14, 15, 16, 17 or 18 inches. Backrest height is available from 8 to 20 inches in 1-inch increments. The backrest angle is adjustable from 90 to 100 degrees, and there is a 7075 aluminum CNC water-jet cut backrest plate. UPHOLSTERY: Laminated carbon fiber sailcloth adjustable by tension cord. CASTERS: 12.5-inch diameter, 2.25-inch wide casters. WHEELS: Spinergy SLX wheels, 25 inches in diameter, with silver anodized handrims. Fits standard mountain bike tires (not included). Six degrees of camber is standard. FOOTRESTS: Single-piece footrest. WEIGHT: 28 pounds. WARRANTY: Lifetime limited warranty on frame.