S608-2RS Sealed Ball Bearings Stainless Steel Ceramic Balls Si3N4 S608-2RS Ball Bearings are double sealed, radial and deep groove ball bearings,S608-2RS bearings are made of Stainless Steel with Si3N4 Ceramic (Silicon Nitride) balls, S608-2RS bearings are closed with rubber seals to protect the bearing from dust or any possible contamination,