We are proud to introduce the Hellfighter mod kit, the perfect, ultra-fast California compliant magazine lock solution for your AR-15. This comes after a year of engineering and countless attempts to make the best and simplest solution on the market. With this bolt on solution (patent pending), you will be able to perform magazine changes faster than you ever thought possible. One of the features that sets us apart is our modified quick-release take down pin, which acts as a button to separate the upper from the lower just enough to disengage semi-automatic operation and automatically disable the magazine lock. Once your upper is separated and disengaged from semi-automatic operation, your magazine release is now operable. A simple tap closes the upper and re-engages the spring loaded take down pin and will quickly get you back in the fight. The Hellfighter mod kit is compatible with any mil-spec AR-15. Features: Ultra fast magazine changes Easy to install in 30 min or less Featureless AR components no longer needed No need to permanently modify your upper or lower No need for bullet button 100% made in USA Patent Pending Design