Use the blackrollreg duoball 12 for punctual massage of back and neck you can use it on a table wall or on the floor a great tool to use for regeneration and mobilisation of muscles and fascia for punctual use massage of the deeper lying muscle groups suitable for massage of the upper arms deltoid pectoralis and calf the space between the two balls also allows a targeted and effective massage around the spine improve flexibility and performance of the muscles use on a