Buy it on Amazon SAFE LONG-LASTING HEAT: Air-activated, unscented, and ready to use. Heat duration lasts up to 10 hours (Regular) and 18 hours (Large). Max temperature: Regular - 160°F (71°C) / Large - 165°F (74°C) Average temperature: Regular - 136°F (58°C) / Large - 142°F (61°C). Do not place the warmer directly on your skin. HEATS UP QUICKLY: Simply remove the IRIS USA long-lasting hand warmer from the package and gently shake to begin warming. It reaches the maximum temperature in as little as 15 minutes. Now you can place it over your clothes or in your pocket for safe on-the-go heating for up to 10 hours. If the temperature of the warmer starts to decrease, gently massage the pouch to reheat. ON THE GO: These single-use hand warmers are available in 2 convenient sizes; Regular (3.7" x 2.7") and Large (4.8" x 3.7"). Travel-sized and TSA approved. IRIS hand warmers provide a comfortable heat and are ideal for keeping your body warm when the temperature gets cold. Outdoor sports, concerts, other events, skiing, biking, hunting, fishing, camping, hiking, yardwork, jogging, or walking your dog. Highly recommended for winter emergency kits! ALL-NATURAL & DISPOSABLE: The only ingredients are: iron powder, water, vermiculite, activated charcoal, salt, and high water absorption resin. Made in Japan. Safe to dispose of after use in compliance with your local regulations. Estimated shelf life of 4 years from the production date on the package. Always ready whenever you need it. OPEN AND GO: Open the package and remove the warmer. Gently shake the warmer and place it over your clothes or in your pocket. If the temperature decreases while you are using it, gently massage the pouch. That's all!