Feature:1. Suitable for the rear hub barrel shaft to open 142mm to 148mm, and the quick release device is used to install and fix the wheels.2. Made of high quality aluminium alloy material, which is high strength, antirust, nondeformation and durable.3. To adapt to the corresponding disc brake disc position and the demand of opening gear, solved the problem of compatibility between hub and rear wheel and frame.4. The disc brake adapter has stable performance,high reliability. Exquisite workmanship, stylish and generous appearance.5. Comes with necessary accessories, easy to install and convenient to use. Useful accessory for bike lovers to DIY bikeSpecification:Item Type: Boost Hub AdapterMaterial: Aluminum AlloyColor: BlackSpecification: Rear 12MM hub barrel shaft to open 142mm to 148mmHub Adapter Thickness: Approx.3mm / 0.12inSpacer Thickness: Approx.3mm / 0.12inOuter Diameter: Approx.5.2cm / 2.0inInner Diameter: Approx.4cm / 1.6inApplication: Suitable for the rear hub barrel shaft to open 142mm to 148mm, in order to adapt to the corresponding disc brake disc position and the demand of opening gear, solved the problem of compatibility between hub and rear wheel and frame..Package List:1 x Boost Hub Adapter1 x Pair of Spacer6 x ScrewNote:1. Please allow 12mm error due to manual measurement. Thanks for your understanding.2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard.