SMR52ZZ Shielded Ball Bearing 2mm x 5mm x 2.5mm SMR52ZZ Shielded Ball Bearing, SMR52ZZ is radial and deep groove ball bearing,SMR52ZZ is made of stainless Steel with stainless Steel balls and steel cage,bearing is closed with metal shields to protect the bearing from dust or any possible contamination,SMR52ZZ is shielded and self lubricated,inner diameter is 2mm, outer diameter is 5mm and width is 2.5mm,the quality is set to EMQ (electric motor quality) to ensure high speed,bearing is lubricated with grease.