Cross Armory's Safe Mag is a magazine locking system modification, designed in California, for weapons in regulated states that require fixed magazines. It prevents the removal of the magazine from your rifle without disassembly of the action when properly installed. The Cross Armory Safe Mag is easy to install and works by releasing your magazine instantly when you separate the upper and lower receivers of your firearm (which disables the firearm action), without having to press a button. The Safe Mag also allows for insertion of a new magazine when the upper receiver and lower receiver are closed, without bending or stressing the hardware of the weapon or the Safe Mag. This Safe Mag is the MIL-SPEC AR-15/M4 configuration which is compatible with AR-15/M4 firearms, Mil-Spec only.Cross Armory's Safe Mag is a modification, designed in California, for weapons in regulated states that require fixed magazines. The Cross Armory Safe Mag works by releasing your magazine instantly when you separate the upper and lower receivers of your AR-15 or M4, without having to press a button. Cross Armory's Safe Mag is intended to be consistent with the fixed magazine laws which state that your weapon must have a fixed magazine which has been defined as an ammunition feeding device contained in, or permanently attached to, a firearm in such a manner that the device can not be removed without disassembly of the firearm action. The firearm action of an AR-15 and M4 is housed in the upper and lower receivers. Separating the upper and lower receiver to release your magazine disables the firearm action. Cross Armory's Safe Mag also allows for insertion of a new magazine when the upper receiver and lower receiver are closed, without bending or stressing the hardware of the weapon or of Safe Mag. Cross Armory's Safe Mag is a reliable, durable and easy-to-install magazine release. When paired with the Cross Armory's QUICK PINS, magazine changes can be performed efficiently and with a minimum of inconvenience to the user. Feature: Fixed magazine locking system for MIL-SPEC AR-15 and M4 rifles Automatic magazine release when upper and lower receivers are separated, no need to push a button Quick and safe fixed magazine release device Safe Mag prevents the removal of the magazine from your AR-15 or M4 rifle without disassembly of the action when properly installed Quick, easy installation Reload easier when separating the upper from the lower receiver