I was looking for a one-piece metal ball for foot rolling for plantar fasciitis pain. I ordered two and they are perfect. You can freeze them on an ice ball for myofascial relief, and it's a little smaller than a golf ball. If you roll your legs frequently, you'll understand that you may need different diameter balls for myofascial trigger points. Normally a golf ball, this 1 1/2" steel bearing and 1" ring is perfect!