Bones Swiss Ceramic Bearings 8mm 16 Pack The Cerbec Ceramic balls are much lighter, harder, stronger, waterproof, and longer lasting than the finest steel balls Bones Swiss Ceramics are in a class by themselves. If you want the best there is, this is it Accelerate faster, roll faster and farther, resist dirt and moisture better. High speed Nylon ball retainer for greater strength and speed set of 16 - for one pair of roller skates Skate Rated clearances, tolerances, materials and lubricant provide the best performance and durability possible