With ACER Racing's National and World Champion reputation in the high performance ball bearing industry we set out to engineer the best ceramic skate bearing at any price. These are 608 size with an inner diameter of 8mm, outer diameter of 22mm and width of 7mm. If you need a 7mm inner diameter Ceramic Skate Bearing please choose ASIN B07197SCQL First we started with our tried and tested Ceramic Nitride Pro Series silicon nitride balls (Si3N4). The same super hard balls that gave us the reputation as \"the hardest balls in the industry.\"" These balls are matched for consistent concentricity per set. They are polished using diamonds for a super smooth and shiny finish. Their durability is unmatched by any other ball or material in the industry. With a melting temperature of 2552 degrees F and the best modulus of elasticity in the world
rest assured you will be running the finest ball bearings in the industry."
