6903ZZ Shielded Ball Bearings 17mm x 30mm x 7mm 6903ZZ Shielded Ball Bearing, 6903ZZ Bearings are made of Chrome Steel, Bearing inner diameter is 17mm, Bearing outer diameter is 30mm and Bearing width is 7mm, 6903ZZ bearing has 2 metal shields to protect the bearing from dust or any possible contamination, 6903ZZ bearings are pre-lubricated with grease.