3 x 6 x 2.5 Stainless Steel Ball Bearing One Bearing 3 x 6 x 2.5 Stainless Steel Ball Bearing, this is a popular size that could be used in many application that uses this size 3mm x 6mm x 2.5mm. Bearing is made of Stainless Steel, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearing is pre-lubricated with grease.