Specification: Item Type: Boost Hub Adapter Material: Aluminum Alloy Color: Black Specification: Rear 12MM hub barrel shaft to open 142mm to 148mm Hub Adapter Thickness: Approx.m / 0.12in Spacer Thickness: Approx.m / 0.12in Outer Diameter: Approx.5.2cm / 2.0in Inner Diameter: Approx.4cm / 1.6in 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. Package List: 1 x Boost Hub Adapter 1 x Pair of Spacer 6 x Screw Note: betweendiv>1. Please allow 1‑2mm error due to manual measurement. Thanks for your understanding.between/div>betweendiv>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.between/div>betweendiv>betweenbr>between/div>