The Tiger Ball Massage-on-a-Rope is perfect for massaging and busting out muscle knots in the piriformis, hamstrings, hips, glutes and other spots wanting deep pressure. Simply lean up against a wall or lie down on the ground and press away. The Tiger Ball Massage-on-a-Rope measures 2.6 inches in length and is great for those with muscle knots in the upper back and shoulders.