Bones Swiss Ceramics are in a class by themselves. If you want the best there is, this is it. The Cerbec® ceramic balls are much lighter, harder, stronger, and longer lasting than the finest steel balls. Resist dirt and moisture better. High speed nylon ball retainer for greater strength and speed. Skate Rated™ clearances, tolerances, materials and lubricant provide the best performance and durability possible. Set of 8 bearings. Imported.