Midwest Midwest Quiet Air Dental Bearings Stainless Steel ABEC-7 Torlon retainer :: Solid SI3N4 Ceramic Balls Two Ball Bearing (one flanged and one straight) Ceramic Hybrid ABEC-7 Ball Bearings that fits Midwest Dental Quiet Air handpiece. One Flanged and one straight Stainless Steel bearings with 7 solid Si3N4 (Silicon Nitride) Ceramic Balls, every bearing is one side Metal shield, Bearings are made of Stainless Steel and has Solid Si3N4 Ceramic balls (SI3N4). Cage is made of Torlon for lowest fricion, long life and highest speeds. We guarantee our bearings and your staisfaction or your money back with no questions asked (please read our feedback).