The Alpha-Brite Lite Stick is a replacement with an 8-10 hour battery life.
The three-piece Alpha-Brite Lighted Nock System includes a Nock-Receiver insert, LED unit, and translucent Alpha-Brite nock. Glue the Nock-Receiver into the arrow, insert the LED unit into the nock, and snap both into place. Firing the crossbow activates the LED, while removing and pulling the LED unit turns it off. Battery lasts about eight hours. Sold in a three-pack.