The design of the back pad encourages extension of the low back muscles while minimizing hip extension. Start point setting for comfort and safety; Back pad position adjusts for optimal placement depending on user preference; Incremental 3.3 and 6.6 lb (1.5 and 3 kg ) micro-loading adjustment; Cold rolled steel weight stacks with noise dampening; Stainless steel guide rods resist rust and stay smooth; Kevlar belts for quiet, smooth action and optimal tensile strength; belt contains 2200 lb (998 kg) tensile strength aircraft cables.; Marine-grade double stitched upholstery.