The Aktiv AQUA Ball is a water fillable, reinforced PVC ball that delivers a unique stabilization challenge during functional movement. This dynamic stability increases the intensity of any exercise to offer new challenges. The Aktiv® AQUA Ball is a safe and effective way to train every muscle in your body. Ideal for at home, outside, boot camp, and athletic training. For a unique resistance training experience. Train Unpredictably™ with Aktiv AQUA; holds up to 6.6 gallons.