Universal DISC Sprocket Adapter 44mm for Bicycle Hub Motorized Bike 1/4 Thick Can be used to attach various sprockets or brake rotors to Bicycle DISC Hubs.Thickness: .25"inch, 6.38mmInner Bore Diameter: 35.8mmOuter Diameter: 108mm, 4.25"inchesDISC Brake Bolt Circle: Standard 44mm3 point sprocket adapter bolt circleMaterial: AluminumCan easily be drilled for your application.Made in USA