The Mini Logo Bearing 608z are Skate Rated, made to Skate One specifications. These bearings were designed for skating, not electric motors. They have a removable rubber shield on one side, a removable metal shield on the other, a high speed molded ball retainer, precision ground and super-finished hardened chromium steel races and balls, and come pre-lubricated with Speed Cream™. This makes them smooth, fast, easy to install and maintain. Mini-Logo Bearings are twice the performance and at half the price you would expect.