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. Upon firing the crossbow, the bowstring’s force compresses the two pieces and activates the lighted nock.Deactivate the easy on/off Alpha-Blaze lighted nock by pulling the nock straight out until the light turns off – no tools required. The LED light of the Alpha-Blaze system lasts for approximately eight hours when activated.The system features TenPoint’s Alpha-Nock HP that is equipped with an HP Aluminum Bushing for increased strength and accuracy.The most accurate crossbow arrow ever, the CenterPunch 20-inch crossbow bolt is fletched slightly offset and is fitted with an 84-grain insert and TenPoint’s Alpha-Blaze Lighted Nock. Constructed from modulus carbon fiber at 33 MSI (million-pounds-per-square-inch) and wrapped in an exclusive LAZER-TECH carbon weave, it is fletched with 3.5″ Bohning X Vanes™. EVO-X CenterPunch crossbow bolts are inspected for straightness to within .001-inch and each package is weight-grain matched to within 1-grain per arrow.The Alpha-Nock can be used in any TenPoint, Wicked Ridge, or Horton Crossbow Innovations crossbow. Use of the Alpha-Nock HP in any of these crossbows will not void the warranty, even if your crossbow originally required the use of a flat nock or Omni-Nock.Specs: Straightness: .001" F.O.C.: 17.5% Inside Diameter: .297 Outside Diameter: .348