Squeeze balls with bag. Whether athletes or office workers, older adults or those with hand injuries: hands are subjected to various strains. With the finger trainer balls in a set of three, you can strengthen your fingers, wrists, and forearms. Each ball has a different level of hardness, allowing for varying degrees of compression. The hand trainers also serve as stress balls after a long, hectic day. Transporting the balls is incredibly easy thanks to the drawstring bag.