SR1038ZZ Shielded Stainless Steel Premium ABEC-5 Ball Bearing 7 Solid SI3N4 Ceramic Balls 3/8" x 5/8" x 5/32" inch SR1038ZZ Shielded Premium ABEC-5 Ball Bearing, bearing is Stainless Steel bearing with 7 solid SI3N4 Ceramic Balls, Bearing is made of Stainless Steel and has Solid Ceramic balls (SI3N4).