This key will open 99% of the handcuffs in use by law enforcement and security departments in North America and much of the rest of the world.  Top handcuffs makers such as Smith and Wesson, Peerless, and Hiatts and dozens of generic brands all design most of their handcuffs, leg irons, etc. to open using a single key. Buy several to have around. You never know when you may need one.