Feature: Aluminum alloy headset top cap bike fork expander bung for 28.6mm / 1.1in. Replaces conventional star nut and top cap, a must for bike steerers. Can be used repeatedly, bite tight, does not hurt the fork, a must-have for top-grade bicycles. Eliminating the of damage and providing added support to the fragile top edge of the steerer. Just use the hex wrench and then you'll get it installed in minutes. Specification:Condition: Brand NewMaterial: Aluminum AlloyColor: Black, Red, Blue, Golden (Optional)Outer Diameter of Stem Cover: Approx. 31.8mm / 1.3inWeight: Approx. 50-55gCore Expansion Range: Approx. 22.2-25.4mm / 0.87-1.00inPackage List:1 * Bike Stem Headset