Ball Bearings 6901 ZZ 12 x 24 x 6 Lot of 10 Bearings 10 Ball Bearings ( 6901ZZ ), the inner diameter is 12, outer diameter is 24 and the width is 6, this is a popular size that could be used in many applications, Bearings are made of Chrome Steel and can rotate up to 23000 rpm, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease, Bearings are packed 10 bearings in one plastic tube.