Origin-8's Pro Pulsion Carbon Expander is an expander and top cap for forks with carbon steerers. Instead of a traditional star nut (which will damage carbon), the Expander snugs tightly and safely in place in the fork for easy and accurate headset adjustments. Plus, it actually strengthens the fork. It fits most 1 1/8-inch forks, and includes a top cap with a stainless-steel bolt.
For 1 1/8-inch forks