Precise contact points for controlled arrow release. Aligned nock barrel for true arrow flight. Concentric design to center the nock in the arrow shaft for more consistent performance. Lightest weight and perfectly balanced for superior accuracy. Lightweight design does not reduce arrow front of center. High visibility. Long-Life battery (8 hours) Green, Blue and Pink ( 50 hours). Release activated. Each nock is manufactured to the highest standards and engineered with 4-axis straightest within 0.001".