R156ZZ Shielded Ball Bearings 3/16" x 5/16" x 1/8" inch Lot of 10 Bearings R156ZZ Shielded Ball Bearings, the inner diameter is 3/16", outer diameter is 5/16" and the width is 1/8", each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.