PU10X40X12 Tire PU Covered Bearing 10X40X12mm Sealed Miniature - tirePU10X40X12 Tire Polyurethane Rubber sealed Ball Bearing 10mm x 40mm x12mm 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. PU10X40X12 Ball Bearing Deep Groove Ball Bearing Material: Cr15 bearing steel