The Nockturnal Half Moon Crossbow Bolt Nocks by Rage allow you to keep track of your arrow flight, shot placement, and arrow retrieval. Clear nock construction with a red LED light in the center for complete visibility. Bowstring activated on-off switch for fast and easy use. These Nockturnal Red Half Moon Nocks are compatible with all crossbow bolts. No assembly required. Comes in pack of 3.