61903RS Sealed Ball Bearing 17 x 30 x 7 mm 61903RS Sealed Ball Bearing, inner diameter is 17mm, outer diameter is 30mm and width is 7mm,61903RS is a popular size that could be used in many applications,Bearing is made of Chrome Steel,bearing has 2 built-in rubber seals to protect the bearing from dust or any possible contamination,61903RS bearing is pre-lubricated with grease.