S683ZZ Ceramic ABEC-5 Ball Bearing Stainless Steel with Si3N4 Ceramic Balls (Silicon Nitride) 3mm x 7mm x 3mm S683ZZ Stainless Steel Ball Bearing with Ceramic Balls ABEC-5 quality, this is a popular size that could be used in many application that uses this size 3mm x 7mm x 3mm. Bearing is made of Stainless Steel, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, Ceramic Balls are the highest standard of balls that can make your bearing live at least 5 times more than any other bearings.