As you know Hyperice makes durable, high quality products. As of this writing, the Hypersphere comes in two sizes: the original size at a 5-inch diameter and the mini at a 3-inch diameter. Each comes with three speed settings and a rechargeable battery with an impressively long battery life. Both are TSA approved and easy to carry during any type of travel (my 5-inch Hypersphere has traveled with me to over 20 countries),
The link above will direct you to the 5-inch ball. We find this size to be optimal. You can search their website and find other products, as well.