Nockturnal Strobing Universal Fit Nocks Red/BlueNockturnal is the leading designer and manufacturer of lighted nocks for arrows and crossbow bolts. Its unique, patented, string activated, linear switch with piston driven assembly ensures activation of the LED bulb every time. They feature super bright LEDs and long life lithium batteries for superior illumination that lasts. Available in a wide variety of sizes and configurations that fit nearly any size arrow or shaft, these specialty nocks