Abstract: This device selectively locks the trigger of a firearm by the action of a hollow pin that, pushed by a spring, fits inside a cavity made at the bottom of the trigger. This hollow pin is welded to a flat steel bar that fits along a groove inside the horizontal part of the trigger guard. This trigger guard is made of a non-magnetizable material. The flat steel bar pivots by the use of a horizontal pin that can be locked at the front of the trigger guard, depending of the needs of the designers of the different guns. This flat steel bar has an up and down motion to lock and unlock the trigger.To release the trigger, the user of the gun wears a flat magnet with a magnetization pattern parallel to its thickness. This magnet should be attached to the exterior surface of the second phalanx of the middle finger of the shooting hand either mounted to a ring or sewn to a glove.