Reflex balls are simply headbands with a tennis ball sized ball attached to them with an elastic string. The idea is to continue to punch the ball and keep it moving with your fists, sort of like a paddleball. Additionally, since reflex balls are completely self-contained, it offers more mobility than other similar pieces of training equipment. For example, boxers can combine their movements with slips and blocks to incorporate full body movements. It helps greatly with improving the timing and accuracy of punches. Like the cobra bag, the accuracy requirement with this piece of equipment creates a steep learning curve to beginners.