686ZZ Shielded Ball Bearings 6mm x 13mm x 5mm 10 Bearings Set of 10 686ZZ Shielded Ball Bearings, Bearings are made of Chrome Steel, this is a popular size that could be used in many RC Cars and Trucks, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with grease.