Ball Bearings Flanged Bearings 3x9x4 Lot of 10 Bearings High Quality 10 Ball Bearings, the inner diameter is 3, outer diameter is 9 and the width is 4, 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.