SR16-2RS ABEC-5 Sealed Bearing Si3N4 Ceramic - 1" ID x 2" OD x 1/2" Width BearingSR16 2RS Sealed Ball Bearing Premium ABEC 5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 1" x 2" x 1 2" Inch SR16 2RS Bearing is double sealed, radial and deep groove ball bearing,SR16 2RS bearing is made from stainless steel with Ceramic Balls (Si3N4) and Stainless steel cage,bearing is closed with rubber seals to protect the bearing from dust or any possible contamination,SR16 2RS bearing is sealed and self lubricated,the quality is set to EMQ