3-Pack with Alpha-Blaze Lighted 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. 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 16-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 2.1 Q2i Fusion-II. 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. Product Specifications Straightness: .001" Grain Weight Tolerance: +/- 1-grain per pack Weight : 400-grains F.O.C: 17.5% Vane : 2.1" Q2i Fusion-II Inside Diameter : .297 Outside Diameter: .348