Oil Seal: According to different working conditions, the materials of oil seal are nitrile rubber, polyacrylate rubber, silicone rubber, fluoro carbon rubber, etc. Specification Range: 6 mm (Diameter of Axle) ×16 mm (Outer Diameter) ×7 mm (Width)~300 mm (Diameter of Axle) ×360 mm (Outer Diameter) ×25 mm (Width).