HIGH VISIBILITY LIGHTS - Shoot it at dusk, and with 20+ hours of battery life, you can still find your arrow the next day. NO ASSEMBLY REQUIRED - Nocks can go straight form the package to the shaft in fully operational condition. No prep work needed. Just 20+ hours of battery life Fits arrows with Inside Diameter of .246 Piston driven contact switch ensures L.E.D. illumination every time Waterproof and shock resistant design is second to none No assembly required