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