This is a pack of two optional XRAY 13x19x4mm Rubber Sealed High-Speed Ball Bearings. These high quality ball-bearings are fitted with special rubber covers, and are degreased and lightly filled with special grease for maximum smoothness, long life, highest tolerance and maximum performance.
These ball-bearings have more (and larger) balls inside the cage than the regular ball-bearings, making them much more resilient under loads. The side covers are easy to remove for quick and comfortable servicing.
These ultra-high precision ball bearings are designed to withstand all extremes at the track under racing conditions or even just fun racing.