Blackroll Duoball, Black, 10.6" x 4.7" x 4.7" Double Ball Ideal for use on the back as the space between the two balls allows for a massage around the spine Use for an effective and targeted massage of the spine, upper arms, deltoids, calf muscles and other body parts Premium design is german-made and environmentally friendly Material is water resistant, easy-to-clean and odorless The perfect myofascial release tool for crossfit, yoga, pilates, weight training, bodybuilding, mma and other exercise activities