Simple to track and easy to recover, Carbon Express Launchpad Precision Lighted Nocks can also improve the accuracy of your shot. Featuring precise contact points, an aligned knock barrel and a concentric design to help center the arrow shaft for truer flight and more consistent accuracy. The lightweight construction won't interfere with the arrow's front of center either. The highly visible LED is release activated and boasts an extra-long battery life. Fits all Carbon Express carbon hunting arrows and arrows with an internal shaft diameter of .244" to .246".