from a numbered photoset, not sure if it was intended for publication or personal enjoyment, ca. 1960s.
One new wrinkle on bondage today v. the 1960s: you'll rarely see real people hanging backwards from metal handcuffs on bare wrists like that anymore, thank goodness. That's a recipe for accidental sprains and injuries. These days, serious bondagists favor padded or customized restraints which reduce the risk of unwanted pain. ...y'know, so we can focus on the wanted pain.