S606 Open Ball Bearing Premium ABEC-5 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 6mm x 17mm x 6mm S606 Bearing is Open radial, deep groove ball bearing,S606 bearing is made of Stainless Steel with Ceramic Balls (Si3N4) and nylon cage, the quality is set to EMQ (Premium ABEC-5 quality), inner diameter is 6mm, outer diameter is 17mm and width is 6mm.