607-2RS Sealed Bearing ABEC-5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 607-2RS Bearing is categorized as thick section, double sealed, radial and deep groove ball bearing,607-2RS bearing is made of Chrome Steel with Ceramic Ball (Si3N4) and Chrome steel cage,607-2RS bearing is closed with rubber seals to protect the bearing from dust or any possible contamination,607-2RS bearing is sealed and self lubricated,the quality is set to EMQ (ABEC-5 quality) to ensure high speeds, 607-2RS bearing is lubricated with grease.