S6902-2RS Premium ABEC-7 Stainless Steel Sealed Ball Bearing 15mm x 28mm x 7mm One Bearing S6902-2RS Premium ABEC-7 Stainless Steel Sealed Ball Bearing, Bearing is made of Stainless Steel, each bearing has 2 Rubber Seal to protect the bearing from dust or any possible contamination, also bearing is pre-lubricated with grease.