Advancing the lighted nock design by which all others are judged, Nockturnal Shift FIT lighted nocks take the simplicity and reliability of the world's most dependable and user-friendly lighted nock to an entirely new level. Thanks to the external on/off switch the process of turning an ultra-bright, string activated Nockturnal lighted nock off has never been easier. Just slide the switch and the nock turns off. It's that simple! With 20+ hours of long-lasting battery life and a durable design, these nocks are built to last and perform like no other. Constructed of an ultra-strong, impact resistant, polycarbonate casing that protects the super-bright LED lights, Shift nocks deliver on what users have come to expect from Nockturnal. The patented, string-activated, piston-driven contact linear switch triggers the nock to illuminate immediately when the string is released and can be quickly turned off with the external switch, a true evolution in the world's most reliable lighted nock system. Features: Super strong, clear polycarbonate construction. Waterproof and shock-proof. Easy on/off light system. Universal design fits X, H, S, and GT Arrows. Provides up to 20 hours of lithium-powered battery life. 3 nocks per package; Each nock weighs approximately 25 grains.