I love slam balls. they provide a great aerobic and strength exercise. I gave only 3 stars, because this ball does not hold a full capacity of air. I like my slam balls on the firm side. I pumped in air, but the air escapes, leaving the ball on the soft side and deforming the round shape of the ball. I don't have this problem with my other slam balls. BALL STILL SERVES IT'S FUMCTION AND I ENJOY USING IT.
I love slam balls. I use it daily as a supplement to my workout. the ball is filled with sand and if it underinflated, the ball will lose its round shape, when it is slammed to the floor. just pump in some air to avoid this. this ball seems durable with a good grip. it is aerobic and a strength builder. it is a functional exercise to lift the ball from the floor to overhead and then slam it down to the floor. I love doing it.