6701-2RS Ball Bearing with Ceramic Balls , this is a popular size that could be used in many fishing reels or any application that uses this size 12mm x 18mm x 4mm. Bearing is made of Chrome Steel, each bearing has 2 Rubber Seals to protect the bearing from dust or any possible contamination, also bearing is pre-lubricated with grease, Ceramic Balls are the highest standard of balls that can make your bearings live at least 5 times more than any other bearing.