Ball Bearings 3x10x4 Stainless Steel Lot of 10 Bearings High Quality 10 bearings Stainless Steel Ball Bearings , this is a popular size that could be used in many application that uses this size 3mm x 10mm x 4mm. Bearings are made of Stainless Steel, each bearing are rubber sealed from both sides to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.