Kela Bear Toes Warmer Air Activated Foot Warmers with Adhesive. Up to 6-8 Hours. Do not directly contact with the skin.Users should allow 10 to 20 minutes for the warmers to reach their optimal temperatures . Toe warmers designed to keep feet warm when skiing, hiking and hanging out Heats up restricted air environment of shoe or boot for up to 6-8 hours Adhesive backing adheres to outside of sock underneath the toes; ultra-thin for comfort Nontoxic, nonflammable, contains all natural ingredients