3 mm Slot Car Axle Ball Bearings 2 Pairs (4 Bearings) 2 Pairs (4 bearings) 3 mm Axle Slot Car Flanged Ball Bearings, size is 3 mm X 6 mm X 2.5 mm, metal shielded bearings, bearings are made of Chrome Steel, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, bearings are pre-lubricated with grease.