Specifications: Oil-free self-lubricating, ceramic ball with oil-free self-lubricating properties, so ceramic ball bearings cannot grease. Insulation, rolling body with ceramic ball, you can achieve the bearing between the inner and outer ring insulation. High speed, the use of ceramic ball speed than the general bearing speed is much higher. Long life, ordinary bearings in the water and high temperature environment, the oil is easy to wash or kill, so that the bearings soon bad, the use of ceramic balls as a rolling body, do not worry about these problems. Waterproof: ordinary bearings used in the water, grease washed off, the bearings soon broken, the use of ceramic balls, you can normally use in the water. Type: Ceramic Bearing Material: Steel, Ceramic Features: Durable, Useful, Easy to Use Item Size: 30mm x 42mm x 7mm/1.18" x 1.65" x 0.28" (Approx.) Notes: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement. Package Includes: 2 x Ceramic Bearings