Construction: Cylinder Tube : For bore of 19, 25, 40, and 50 mm hard drawn, polished brass/ aluminum tube and for bores of 65, 75, 100, 125, 150, 200, 250 and 300 mm seamless honed & hard chrome plated steel tube is used. Piston Rod : High tensile steel, Ground & hard chrome plated. Seals : Buna "N" ( Nitrile elastomer ) End cover & piston : Close grained cast iron.