For years, physical rehabilitation centers have used BFR to help people build muscle or reduce muscle loss after things like surgery and accidents. The idea is that by restricting blood as it's leaving a muscle (while allowing oxygenated blood to flow to the muscle unimpeded), you can increase metabolic stress and cellular swelling, leading to increased growth hormone and muscle growth. By lifting less weight, you're also putting less strain on the joints.
The new SmartCuffs are meant to be consumer-friendly, so you can use them at home, at the gym or at work. They're automated so you don't have to manually pump them. They'll automatically shut off if the pressure exceeds a recommended range for each person, and SmartTools says they're more rugged than past iterations.
Previously, you could buy two SmartCuffs for $350. Starting tomorrow, the new model is available for pre-order for $199. The cuffs will start shipping in July, and SmartTools will be demoing them at CES, so if you're going, you can preview them this week.
Update 1/6/2020 10:35AM ET: Originally scheduled to ship in May, the cuffs are now expected to ship in July.