MR52ZZ Shielded Ball Bearings 2 x 5 x 2.5 mm MR52ZZ Shielded Ball Bearings, the inner diameter is 2mm, outer diameter is 5mm and the width is 2.5mm, Bearings are made of Chrome Steel, each bearing has 2 Metal Sheild to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.