The amazing new patent pending Nockturnal lighted nock is a breaktrough design that is more affordable and lighter in weight than most other lighted nocks. The NockTurnal has a string activated linear switch that is protected deep within the nock and will not turn on or off inadvertently. Battery last over 20 hours. Made of clear plastic for maximum light transmission --- can be seen for hundreds of yards. Speed saving ultra-light design... only 20 grains TOTAL weight... most other lighted nocks weigh 25% - 50% more!