The Hellfighter Mod Kit it the perfect, ultra-fast California Compliant magazine lock solution for your AR-15 Or AR-10. Juggernaut's modified quick-release take down pin, acts as a button to separate the upper from the lower just enough to disengage semi-automatic operation and automatically disable the magazine lock. It allows you to keep all of your current features, including a pistol grip, a forward grip and adjustable butt stock.