Never lose an arrow again! Replace your original internal mount nocks with the Lumenok Signature Lighted Nock. Lights up automatically when seated against a carbon or aluminum arrow shaft. Stays lit for up to 40 hours. No magnets, no glue, no switches or moving parts. Light can be disengaged by backing nock out of arrow shaft. Lights up automatically Stays lit up to 40 hours Easy to disengage