Basically a sup leash connects the surfer and the surfboard. If surfers fell off a wave, they can get their board back via the leashes and no need to swim back to shore. A sup leash is a cord made of urethane that attaches the ankle of the surfer to the tail end of a stand-up board. The leash is secured to the surfer's ankle by a Velcro strap, also known as the cuff. It is usually strapped to your ankle but is sometimes strapped to the knee or calf when doing long boarding or paddle boarding. Although originally made out of surgical cord, urethane is a great material for cords. We use Germany and China Taiwan urethane for our sup leashes. They are the best quality in the market and superior in color brilliancy, anti-UV, softness, resilience and security. If you want to check our cord data sheet, please see more info from BASF Germany.