The Shield Magazine Extension fits 9mm and .40 caliber handguns. The extension gives a more comfortable grip, establishing more control over the weapon. Made of polymer and adding a mere 0.5 oz. to the handgun, the Extension easily slips over the existing handle to provide an ergonomic and balanced feel. The Extension also adds room for two more rounds to a 9mm handgun and one more round to a .40 caliber weapon. The kit includes the magazine extension, a locking plate, and a locking plate set screw.