ABI Enduro Zero Ceramic Cartridge Bearings with ABEC 5 Rating.All measurements are in millimetersGrade 3 Balls and Magnetite Rust Proof FinishABEC 5 Precision and Silicone W Seals3 Times Cryogenic Race TreatmentItem SpecificationsBearing I.D.8mmBearing O.D.22mmBearing Thickness7mmManufacturer Number608