Abstract: A safety device for controlling the operation of equipment and most specifically blocking the firing mechanism of a weapon including a plunger having a piston including a magnet section and an actuating rod secured to the piston, the actuating rod being so situated as to block the firing mechanism of the weapon, the plunger being mounted in a sleeve, the operator having a ferromagnetic disk secured to the hand, which causes the magnet section of the piston to withdraw the piston and the actuating rod, the piston and the actuating rod returning to the locked position in the absence of the ferromagnetic disk due to the magnetic draw on the magnet section of the piston either from the weapon itself or in the absence of such magnetic draw from a ferromagnetic disk mounted in the sleeve.