Doubletake Nockturnal St Epic 3-49 Red Nock The amazing new patent pending Nockturnal lighted nock is a break trough 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. It has a speed saving ultra-light design. Most other lighted nocks weigh 25% - 50% more. Clear plastic for maximum light transmission -- can be seen for hundreds of yards!