Nockturnal Launchpad Universal Crossbow Nock - Features: - Durable & Long-Lasting Integrated one-piece aluminum housing protects battery and LED during high-speed flight and impact. - Custom-Fit Micro-Adjustability adjustable barrel end is easy to install and provides a reliable performance fit. - One Size Fits nearly all crossbolt brands and models (comes with 2nd Grey Collet). - Includes reusable c-clip to prevent lighting during storage. - Easy & Reliable On/Off Indexed nock end provides added safety and an easy ON/OFF design. - Available in Red or Green - Each nock in this package weighs approximately 30 grains - 3 per package - The Nockturnal Launchpad Crossbow Nock is easy to install easy to use and specifically engineered to light up every shot with high-visibility LEDs. The lightweight durable design is fully adjustable and can provide a custom precision fit on virtually any brand of crossbow bolts.