Skateboard Wheel & Truck Titanium Hardware by ACER Racing (Ceramic Skateboard Bearings) Description 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, these are the best balls period. We use our special synthetic and American ACER Racing SIN oil lubrication in our ceramic skate bearings which has an extremely wide service temperature range of from -50 to +120 degrees Celsius with an incredible speed factor of 1 million. We integrate our HSR inner ball bearing cage for durability and strength with superior heat resistance at high RPMs. This insures that your ceramic skate bearings will spin faster, longer. We seal our ACER SK8 ceramic skate bearings with two no contact grey seals which will resist the elements while allowing simple removal for easy cleaning when necessary. Each seal is embossed with our trademark "ACER RACING CERAMIC" logo to insure that you are receiving the original ACER SK8 ceramic skate ball bearings. These are the best ceramic skate bearings at any price. Whether used in your skateboard, inline skates, longboard, roller skates, fidget spinners or anywhere a size 608 8x22x7mm ball bearing is used, rest assured you will be running the finest ball bearings in the industry. Features: Diamond Polished Super Light Silicon Nitride Ceramic Balls. ABEC 7. 8mm inner diameter x 22mm outer diameter x 7mm width 608 size Highly polished races with high performance low friction nylon inner cage + proprietary inner tolerances Oiled with ACER Racing's SIN 100% synthetic lightweight oil Sealed on both sides with no contact removable seals Product Details: Brand: ACER Racing Material: Ceramic Item Dimensions LxWxH: 3 x 1 x 3 inches Item Weight: 0.09 Pounds Bearing Number: 608 Brand: ‎ACER Racing Material: ‎Ceramic Item Dimensions LxWxH: ‎3 x 1 x 3 inches Item Weight: ‎0.09 Pounds Bearing Number: ‎608 Bearing Type: ‎Ball Bearing Compatible Lubricant: ‎Oil Item Package Dimensions L x W x H: ‎4.5 x 2.3 x 0.4 inches Package Weight: ‎0.04 Kilograms Brand Name: ‎ACER Racing Color: ‎Titanium Manufacturer: ‎ACER Racing Part Number: ‎B005HZADBYFBA Size: ‎Ceramic Skateboard Bearings Date First Available: July 15, 2012