FR2-5ZZ Flanged Ball Bearing with Ceramic Balls 1/8" x 5/16" x 9/64" inch FR2-5ZZ Flanged Ball Bearing with Ceramic Balls, this is a popular size that be used in many application that uses 1/8" x 5/16" x 9/64" inch. 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.