Ball Bearings 6 mmx 13 mm x 6 mm One Bearing One Ball Bearing the inner diameter is 6, outer diameter is 13 and the width is 6, 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.