Axe Lighted 19in Carbon Crossbow Bolts - 3 Pack - These lighted nocks are exceptionally reliable and do not require any specific tools to set up and come factory-installed in the shafts. Side illumination ports on the nock's body allow for additional light dispersion and increased "tracking" as the nock moves. With more than 20 hours of lithium-powered battery life the extended burn time grants plenty of opportunity for reuse and easy identification long after the shot. Crossbow String Activated Injection Molded Super bright LED 20+ hours Approx. Weight: 44 grains