A set of early 20th-century "Snaps" handcuffs, aka "Nipper" or "Come Along" cuffs

Such cuffs were intended to be used when escorting a prisoner, for example from a jail cell to the courtroom. The device has no key and relies on a clip to the side of the larger of the two loops for the wrists. The small loop was to be used on the prisoner’s wrist while the larger was for the police officer. Many forces did not use these, given that it was very easy to inadvertently break a prisoner's wrist.