The BLACKROLL Duoball allows for a targeted and effective massage of the spine, upper arms, deltoid, pectoralis, and calf muscles. Use by laying on the floor or against a wall. This product is ideal for use on the back. The space between the two balls allows for a targeted massage around the spine. The BLACKROLL Duoball is environmentally friendly as it is made using an energy-saving production process and it is free of propellants and chemicals. This German-made product is easy-to-clean, water resistant and odorless.