There are reasons that the U.S.A. Made Dynamax Balls are the most commonly used medicine balls in the CrossFit community.
They were developed by Track and Field coach, Jim Cawley to help his athletes develop the 10 adaptations to physical training that he had eneumerated.
In order to accomplish this, he needed balls that could be caught by his athletes no matter how hard they were thrown. At the time, the medicine balls that were available were firm, which limited the movements that could be performed safely. He developed a 14 inch ball that had enough padding, even at 20 or 30 pounds, to be used safely for high velocity movements.
They are extremely durable. They will stand up to years of use in a busy commercial gym. The balls are also available in 2 pound increments from 4 to 20 pounds, as well as 5 pound increments up to 30 pounds, so people at every level of fitness can benefit from the vast array of exercises including: wall ball, overhead throws, glute ham developer wall ball, underhand throws, medicine ball king of the hill, bull in the ring, seated situps, partner throws, medicine ball clean and jerk and snatch.