PU12X40X12-2RS PU Covered Bearing 12x40x12mm - Sealed - MiniaturePU12X40X12 2RS Polyurethane Rubber sealed Ball Bearing 12mm x 40mm x 12mm Polyurethane ( PU) is a new type of polymer composite materials between rubber and plastic, offering higher load bearing capacity compared to plastic, polyurethane offer superior impact resistance, while good mechanical properties. Polyurethane have better abrasion and tear resistance than rubber. PU12X40X12 2RS Ball Bearing Deep Groove Ball Bearing Material: GCr15 bearing steel