7mm ID bearings are almost exclusively for Roller Skates. These bearings WILL NOT WORK WITH SKATEBOARDING OR ROLLER HOCKEY SKATES. Bones Swiss Ceramics are in a class by themselves. If you want the best there is, this is it. The ceramic balls are much lighter, harder, stronger, waterproof, and longer lasting than the finest steel balls. Made in Switzerland. Includes 16 Bearings (Enough for 8 Wheels).