Ball Bearings 6905ZZ 25 mmx 42 mm x 9 mm One Bearing One Ball Bearings the inner diameter is 25, outer diameter is 42 and the width is 9, this is a popular size that could be used in many applications, Bearings are made of Chrome Steel, bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.