4-Pack Slot Car Axle Flanged Shielded Bearings 3x6x2.5mm3 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 from high strength Chrome Steel, each Comes with double metal shields (ZZ) to keep out dust and dirt, bearings are pre lubricated with grease. 3 mm Axle Slot Car Bearings Flanged Deep groove ball bearings Shield Double Metal Shields for dust protection (ZZ)