21 Series NCM Construction: Single Acting, Spring Return No. 1 2 3 4 5 6 7 8 9 10 11 Description Material Aluminum alloy Aluminum alloy Stainless steel Aluminum alloy Stainless steel Carbon steel Sintered Bronze Urethane NBR NBR Music wire Aluminum alloy Note Clear anodized Clear anodized Stainless steel 304 Chromated Hard chrome plated Chromated Chromated Rod cover Head cover Cylinder tube Piston Piston rod 3/4", 7/8" 1-1/16", 1-1/4", 1-1/2" Bushing Bumper Piston seal Piston gasket Spring Spring guide Component Parts With bumper