You don't always give much thought to the top cap on your bike, but what if they were done different? Absolute Black has designed one of the best top caps you will ever have. It is a single-piece, bolt and top cap integration with a 5mm Allen (hex) head. Made to fit every standard starnut, but it is not intended to compression plugs (used in carbon steerer). It is compatible with ENVE compression plugs. Specifications: Size (Mass +/-1g): only 4g Key required: Allen 5mm Material: cnc machined 7075 Dimensions: For measuring purpose treat it like 25mm hex bolt. Troubleshooting: If your top cap sits from an angle on the stem (does not touch stem with whole circumference), it means your starnut sits from an angle. You will have to make it straight prior to mounting Ab top cap. To do that you can use old steel bolt and a hammer.