The TenPoint ACU-X Lighted Nock for HP Bushing 3PK 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 ACU-X Snap-On Lighted Nock by pulling the nock straight out until the light turns off. The LED light of the ACU-X Snap-On Lighted Nock system lasts for approximately twenty-four hours when activated. Use of the Bednar Perfect Puller 2.0 makes lighted nock deactivation extremely easy. FeaturesEasy-to-use one-piece ACU-X Snap-On Nock / LED unit - no assembly required515+ FPS approvedFeatures a Nock Retention Groove that allows the user to both hear and feel the positive engagement of the nock to the string on TenPoint rail-less crossbowsBowstring activatedSuper bright LED light provides superior arrow flight visibilityEasy deactivation24-hour battery life when activated (approximate)Feature...