Includes 8 Wheels, 16 Hybid Ceramic Bearings, 8 8mm Spacers, and 8 6mm Stepped Spacers (You only need 1 set of spacers depending on your skates, we inclue both as a courtesy). Premium quality urethane with maximum grip and durability. Perfect for sport court, wood, and smooth concrete. Recommended Surface: Indoor Size and Durometer: 76mm/80mm (HiLo), 74A Amp Hybrid Ceramic bearings are like stimulants for your wheels. With this bearing you get the precision of ceramic and the durability of steel balls. The single Ceramic ball cleans debris and cools friction allowing for a longer lasting bearing.