S6002 Open Ball Bearing ABEC-7 Quality with Si3N4 Ceramic Balls (Silicon Nitride) 15mm x 32mm x 9mm S6002 Open Stainless Steel, radial and 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 speed, inner diameter is 15mm, outer diameter is 32mm and width is 9mm.