With the Lumenok ECC in your crossbow bolts, you'll always be able to trace your bolts in flight and see exactly where your shots fall. Ultra bright LED light activates upon the shot and offers unmatched visibility, making it easy for you to reclaim fired bolts. This lighted bolt end fits Easton Power Bolts and Beman Thunderbolts (.279" ID). Crescent shaped end. For use in Horton, Barnett, Darton, PSE, and Bowtech crossbows.