NEVER LOSE YOUR ARROW AGAIN! Nockturnal is a leading designer and manufacturer of lighted nocks for arrows and crossbow bolts. The Nockturnal nocks patented, unique bow-string-activated, linear switch is piston driven and ensures L.E.D. illumination every time. With no assembly required, Nockturnal nocks feature super-bright LEDs and long-life lithium batteries for superior illumination that lasts. Nockturnal also manufactures the Predator line of lighted crossbow bolts.