Metric size Series K, with solid stainless steel outer ring, is used in low revolution applications, with dynamic loads, and in corrosive environments. Insert is bronze with PTFE liner bonded to inner surface, and ball is 100Cr6 bearing steel, hardened, ground, polished, and hard chrome plated. Bearings without outer ring feature zinc-plated, free-cutting steel insert with PTFE liner bonded to inner surface. Ball is 100Cr6 bearing steel, hardened, ground, and polished.