While Ianto strips, Jack takes the opportunity to divest himself of his shirt and t-shirt, along with his boots. He leaves the trousers on, though, as a visual reminder of their different roles.
He looks Ianto over appreciatively once he's stripped and flicks a hand towards the bed. "Face the end of the bed," he instructs and crosses to the shelf holding the spreader bar in its box. He brings it over to Ianto with a smile and slides the bar out, letting Ianto get a proper first look at it. "Safeword?" he prompts, mostly just for ritual's sake, as he drops down behind Ianto and buckles one cuff around his left ankle, then taps against the inside of his right ankle to make him move it. "Gonna need to spread 'em rather more than that!"