This listing is for 10 piece/s.R21 oil seals are rubber covered case single lip. Commonly used to exclude dust, dirt and water on one side. Protecting bearings against the escape of greases and lubricants. Oil seals can also be know as shaft or lip seals. We recommend that the sealing lip needs a form of lubrication to avoid overheating. Features Flexibility in lip to hold against the rotating part (normally the shaft). Highly Resistant to Chemicals. Styles can include rubber covered, metal cased and totally metal enclosed in either metric or imperial. Materials vary between Nitrile, Viton, Rubber, Silicone and Stainless Steel. Helps to reduce Water, Dirt, Dust or any other substances. Specifications Inside Diameter: 18 mm Outside Diameter: 32 mm Width: 8 mm Series: R21 Material: Nitrile