Item Type: Boost Hub Adapter_x000D_ Material: Aluminum Alloy_x000D_ Color: Black_x000D_ Specification: Rear 12MM hub barrel shaft to open 142mm to 148mm_x000D_ Hub Adapter Thickness: Approx.3mm / 0.12in_x000D_ Spacer Thickness: Approx.3mm / 0.12in_x000D_ Outer Diameter: Approx.5.2cm / 2.0in_x000D_ Inner Diameter: Approx.4cm / 1.6in_x000D_ Application: 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. 1Suitable for the rear hub barrel shaft to open 142mm to 148mm, and the quick release device is used to install and fix the wheels. 2Made of high quality aluminium alloy material, which is high strength, anti?rust, non?deformation and durable. 3To 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. 4The disc brake adapter has stable performance,high reliability. Exquisite workmanship, stylish and generous appearance. 5Comes with necessary accessories, easy to install and convenient to use. Useful accessory for bike lovers to DIY bike 1 x Boost Hub Adapter 1 x Pair of Spacer 6 x Screw 1. Please allow 1?2mm error due to manual measurement. Thanks for your understanding._x000D_ 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.