American Munitions made handcuffs and other restraints for the American Government during the earlier part of the 20th century. These Leg Irons are your typical swing through pattern. They have a rather chunky chain and are in general a little heavier and more substantial than modern ones. They use a solid post key that goes through the entire case and rests in a smaller hole on the other side. The single bit unlocks both the single and double locks. The double lock is similar to modern cuffs and is actuated by depressing it through a small hole in the side of the lock case.