Source of picture: Teasing Video, Cock Teasing - Indecisive Captions
Maybe this should be called an "Edging Belt," as it's purpose is to teach orgasm denial/control through learning self-control. Whatever, here's what it is & how it works:
Naked (of course) he is first fitted with a spreader-bar attached to his ankles (to maintain his legs wide apart) & then a truss-like harness of wide leather waist belt (with a shackle fitted at each side for securing his arms by their wrists) having a fixed leather strap coming down from its front and looping back up (via the crotch) to fasten to its rear.
This strap has two key features: A ring clasp on its front side designed to fit snugly round the base of his otherwise left exposed genitals & provision for securing a butt plug on its backside. Once he is properly secured in this device -- wrists shackled, genitals locked, plug in place -- he is ready to begin his training, to be conducted in this wise: Continuously (ideally for a day) he will be subjected to being mischievously teased, tickled, masturbated to the threshold of orgasm repeatedly-- but not to cause it, denying him it. Indeed, he is forbidden to climax.
The "lesson" here is to learn him not to allow himself orgasm, regardless; the "spur" being he knows that if/whenever he should succumb and ejaculate, he will be made to suffer a whipping on his buttocks & inner-thighs...
This way can be less expensively practiced by simply binding his arms behind him, fitting him with a ring & using a dildo, but however, I can assure you it "works" wondrously...