Advancing the lighted nock design by which all others are judged, the Nockturnal Shift FIT Lighted Nocks take the simplicity and reliabiLightedy 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. The G Shift is sized specifically for .166 ID arrows and offers increased strength and durability from previous models. Features: Bowstring activated linear switch. Super strong, clear polycarbonate construction. Streamlined tool-free on/off switch. 3-pack with universal FIT collars. Fits G sized arrows (.166"). 20+ hour battery life.