61903ZZ Shielded Ball Bearings 17mm x 30mm x 7mm Lot of 10 Bearings Set of 10 61903ZZ Ball Bearings, Bearings are made of Chrome Steel, Bearing inner diameter is 17mm, Bearing outer diameter is 30mm and Bearing width is 7mm, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.