R166ZZ Shielded Ball Bearings 3/16" x 3/8" x 1/8" inch Lot of 10 Bearings R166ZZ Shielded Ball Bearings, the inner diameter is 3/16", outer diameter is 3/8" and the width is 2/16", also bearings are pre-lubricated with grease, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination.