Double Lock Thumb CuffsThumb cuffs first came around for use by detectives & off duty policemen due to their low profile size. These stainless steel thumb cuffs feature a double lock mechanism for convenient and secure use. In single locked mode, the thumb cuffs can pass all the way through the ratchet until the teeth are free on the other side. This allows quick unlocking of the handcuffs in an emergency situation. To put them in double lock mode, a pin on the bottom can