>>Designed to fit a man’s anatomy perfectly with a cool mesh pouch for your sack and a vertical fabric compartment that forces your penis to point up. Made from a soft blend of 95% cotton / 5% spandex, this double fly brief provides unparalleled comfort and a unique wearing experience.
My theory is that it would be as detrimental for penile growth, as it still restricts and holds the penis in a set position. As for the balls, it may feel a little more comfortable, but I doubt it would do anything for growth. Ballmasters like Supra wear ringed devices to put pressure on the scrotum and these may not fit real well using those briefs. That being said, Supra would really be the one to ask.