It's probably the best top cap you will ever have. One piece, bolt & topcap with Allen (hex) 5mm socket. Will fit to every standard starnut. Not suitable for "expanding" star nuts with the steel coil spring (used in carbon steerer). However, it is compatible with ENVE Compression Plug (recommended for carbon steerers).
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 your shiny new AbsoluteBLACK top cap. To do that you can use a starnut setter to correctly align the starnut inside your fork steerer, and then re-fit.