FR188ZZ Flanged Shielded Ball Bearings 1/4" x 1/2" x 3/16" inch Lot of 10 Bearings FR188ZZ Flanged Shielded Ball Bearings, the inner diameter is 1/4", outer diameter is 1/2" and the width is 3/16", this is a popular size that could be used in many applications, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.