SR1-5ZZ Stainless Steel Ball Bearings, the inner diameter is 3/32", outer diameter is 5/16" and the width is 9/64", this is a popular size that could be used in many applications, Bearings are made of Stainless Steel each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.