13 x 19 x 4 Shielded Ball Bearing One Bearing 13 x 19 x 4 Shielded Ball Bearing, the inner diameter is 13mm, outer diameter is 19mm and the width is 4mm, this is a popular size that could be used in many applications, Bearing is made of Chrome Steel, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearing is pre-lubricated with grease.