LIGHTED CROSSBOW NOCKS - The Alpha-Blaze Lighted Nock contains a one-piece Nock/LED unit that is indexed with the vanes and press fits into the arrow’s Aluminum Bushing. ESSENTIAL FOR CROSSBOW HUNTING - The super bright LED on the Alpha-Blaze Lighted Nock provides superior arrow flight visibility to track your shot’s point-of-impact, and lasts for approximately eight hours when activated. Approved for 505+ FPS. EASY ON/OFF - Upon firing the crossbow, the bowstring’s force compresses the two pieces and activates the lighted nock. Deactivate the lighted nock by pulling the nock straight out until the light turns off. COMPATIBILITY - The Alpha-Blaze Lighted Nock fits all TenPoint & Wicked Ridge arrows with an HP Aluminum Busing (sold separately). DON’T SETTLE FOR LESS - With TenPoint, you are arming yourself with a complete hunting system, including accessories specifically engineered to help you fill your freezer or put one in the record books!