MSR Magazine Locking Device.
This button utilizes a set screw to “lock” the magazine in the gun. It disables the button. Once installed you are unable to remove your magazine. This is a solution for citizens that live in the communist states like NY, Ca, and Ct.
Easy to install. No special tools needed. Replaces your existing button. Includes the button, set screw, and allen key.
Installs in less than 1 min.