Increases coordination, cardiovascular endurance and general physical fitness. Sturdy tubular steel frame, rugged polypropylene bed and 36 heavy-duty steel springs. Foam-padded naugahyde covers springs and frame. Complete with no-side rubber feet. 40" (102 cm) Dia. frame; 30" (76 cm) Dia. bed. Weight limit 185 lbs. Use with W4541 stabilizer bar (optional).