Specialized Concave Alloy Top Cap w/ Star Nut Assembly Description: The Specialized Concave Alloy Top Cap w/ Star Nut Assembly is a lightweight top cap and star nut for bicycles with an alloy fork steerer tube. This assembly features a concave alloy top cap, an anodized alloy bolt, and a star nut for an 1 1/8" alloy fork steerer tube. Note: Using a star nut on a carbon fiber steerer may cause damage or failure. Features: Concave alloy cap For 1-1/8" steerer Lightweight anodized alloy bolt 6 flanged star nut For use on alloy steerers