Flexiable Hiatt cuffs

New member here. Wonder if anyone can help with a pair of Hiatt flexiable handcuffs w/one key that I got off e-bay. Key number matches handcuffs. Matching key number to handcuffs any indicater of oringiality. I would think its just as easy to put numbers on repros as it is on authenic cuffs.
Also I have another pair more modern looking with P.E. Rex, wondering what the year of manufacture they are. Will try to post pics as soon as I figure out how to post them.