R156ZZ Shielded Ball Bearing With Ceramic Balls 3/16" x 5/16" x 1/8" inch R156ZZ Shielded Ball Bearing with Ceramic Balls, this is a popular size that could be used in many application that uses this size 3/16" x 5/16" x 1/8". each bearing has 2 metal shields to protect the bearing from dust or any possible contamination.