Designed to allow crossbow shooters to see bolt flight. Lumenok Bolt end has an easily replaceable battery! Use RB- 425. Contains 3 complete carbon bolt assemblies. Bolts are equipped with High Visibility GreenLumenok bolt end, 4" vanes. For use in Horton, Barnett, Darton, PSE, and Bowtech crossbows.BURT COYOTE