Most examples are a later patent date or without a key. This pair has 90% of the original nickel & FIVE patent dates ranging from 1874 to 1882. Also marked "Towers Patent". The three links are the correct twisted style. Has a working key. These cuffs are the double locking type. The first stop allows the cuffs to be tightened past the original setting & a second turn of the key locks them at a particular setting so they can't be over tightened and injure the prisoner. These working keys are somewhat fragile so shouldn't be forced.Directions for proper use is included. (Cat. #19053)