Superior accuracy meets light-up convenience. TenPoint® Pro Elite 400 Carbon Crossbolts are inspected for straightness to within .003" and hand-sorted for weight tolerance to within 2 grains per dozen. Each comes equipped with an Alpha-Blaze Lighted Nock, a one-piece Nock/LED unit indexed with the vanes and press-fitted into the Arrow's bushing. Upon firing, the bowstring's force compresses the 2 pieces and activates the Nock. Deactivation is simple, and the LED will last for about 8 hours when activated.