10 bearings Stainless Steel Ball Bearings with Ceramic Balls ABEC-5 quality, this is a popular size that could be used in many fishing reels or any application that uses this size 3mm x 10mm x 4mm. Bearings are made of Stainless Steel, each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre-lubricated with Oil (not grease), Ceramic Balls are the highest standard of balls that can make your bearings live at least 5 times more than any other bearings.