Hydraulic Seal: According to different working conditions, hydraulic seals can be divided into piston seal, rod seal and piston and rod seal, the materials are nitrile rubber, fluoro carbon rubber, polyurethane, etc. Specification Range: 18 mm (Outer Diameter) ×8 mm (Diameter of Axle) ×7.5 mm (Width)~332 mm (Outer Diameter) ×330 mm (Diameter of Axle)×24 mm (Width).