The realistic, lifelike, slightly flexible properties of the HYDRO-FLEX system makes it react and function like an actual opponent, providing one of the most authentic experiences you’ll get in the gym or at home. An exclusive high-tech PVC rubber Flex-Neck attaches the industrial plastic base for slight flex-action when striking the bag to offer athletes an astounding real opponent feel and action. Because it “gives” on impact, it also helps reduce injuries, prevents hand problems and greatly minimizes long-term wear and tear on your joints. The base conveniently fills with water or sand for excellent stability. Unique design allows the bag to be slightly tilted and easily rolled from the base, to and from training area, to keep it stored out of the way when not in use, if desired.