A patented weighted insole that is easy to use and is good for all sports and aerobic exercises. Designed to increase strength, speed, agility, and vertical. Train with the insoles in your shoes and then replace with your regular insole for competition. Not only does it increase performance, but the S3 provides all the same benefits as a typical orthotic as well. See and feel the improvement and difference! It’s like a medicine ball for your feet to train with!