Lonsdale - Ideal for beginner boxers and fitness enthusiasts looking to improve their agility, endurance and coordination, the Lonsdale Cardio Strike Bag offers the ultimate punching surface. Equipped with a high-density plastic base that can be filled with water or sand, the Cardio Strike Bag offers extreme stability whilst you workout.The inflatable boxing bag has been made from a synthetic polycanvas that offers a comfortable yet sturdy striking surface. Supported by a durable spring neck and EverFlex collar system each punch will be absorbed with maximum efficiency, limiting any movement from the base. Cardio exercise only not for heavy hitting.