Track and Find Your Arrows with Illuminated Nocks 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 none 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 lighted nocks. 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 newly integrated external switch, a true evolution in the world&';s most reliable lighted nock system. Nockturnal Shift Lighted Nock Specifications and Features: Manufacturer Item Number: NT-810Strong Polycarbonate ConstructionWaterproof/Shock ProofExternal Off SwitchBattery Life: 20 HoursInternal Lithium BatteryWeight: 25 GrainsRed LED2-Pack Fits: X, H, S, and GT arrows X (no bushing) Fits smaller diameter carbon .204 ID shaftsH (white bushing) Fits smaller diameter carbon .233 ID shaftsS (gray bushing) Fits standard carbon .244 ID shaftsGT (black bushing) Fits smaller diameter .246 ID shafts