Neoprene exterior insulates the frozen gel pockets keeping the boots colder longer. Smooth nylon lining eliminates the potential for damaging tissue from exposing the skin directly to ice, while also preventing dirt, shavings, and debris from sticking to the inside of the boots. Hook and loop straps with elastic allow for custom fit and keep the boots in place. To activate, place boots in freezer until frozen. Wet leg and boot before application to maximize cold therapy. Recommended use time: 20 minutes