1.Four piece piston seals,Low firction, 2..High pressure operationg conditions 3.Good quality ... and backed by two sprit nylon back-up ring. These seals offer low firction, high pressure operationg conditions.Material: PTFE+Nylon ... :After MarketingCAT, HITCHI, KOMATSU, CATO, KOBELCO, DAEWOO, HYDNDAIOthers earthmoving machine. Hydraulic Cylinder Piston Seal