The amzing new patent pending NockTurnal lighted nock made by Double Take Archery is a breathrough design that is more affordable and lighter in weight than most other lighted nocks. The NockTurnal has a string activated "hidden linear switch" that is protected deep within the nock and will not turn on or off inadvertently. The NockTurnal lighted nock system has a speed saving ultra-light design-other lighted nocks weigh up to twice as much. Battery lasts over 20 hours! NockTurnal lighted nocks require no glue, magnets or assembly.