S627 Open Ball Bearing ABEC-7 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 7mm x 22mm x 7mm S627 open radial deep groove ball bearing, bearing is made of Stainless Steel with Ceramic Balls (Si3N4) and Stainless steel cage, the quality is set to EMQ (ABEC-7 quality) to ensure high speeds, Bearing inner diameter is 7mm, Bearing outer diameter is 22mm and Bearing width is 7mm.