608RS Ball Bearing With Extended inner race 8mm x 22mm x 7mm inner race width=13mm 608RS Ball Bearing With Extended inner race, that will eliminate the use of spacers,you will get more rigid/smooth wheel set when you use this bearing,these bearing is sealed on one side (the outer side) with rubber seal,Bearing is made of Chrome Steel,each bearing have One Rubber Seal to protect the bearing fromdust or any possible contamination.