Review (5/5): Did more than I expected.
I bought one to check out before I got a pack of them. Their purpose is to strengthen the jaw, but mainly to build jawline structure, stretches skin, which can decrease fine lines, and I can confirm that it does all that.
But I had crunchy sounds from slight TMJ up by my ear, and after a few days working out with the Ball, those crunchy sounds left, like the work out worked out a jaw issue of mine. I was pleased about that extra feature.