Ignik XL Warmers are Arctic Grade, designed to solve the biggest problems you face with cheaper air-activated warmers; providing reliable, consistent, and long-lasting heat when you need it and with less waste. Ignik starts with the highest quality, naturally active ingredients. The contents are safe, all-natural, and biodegradable. Their Patent Pending AirBarrier pouch keeps more air out for more reliable heat - up to 24 hours each, more heat than the leading brands. The resealable top gives you control to use the warmers when you need them. Store unused open warmers for up to 72 hours later. The outer pouch is re-usable and 100% recyclable. The end result is a higher performance warmer, which is more efficient and less wasteful. Best of all, they are 98% Biodegradable. When you are finished, just cut the warmer sack and compost the natural chemicals inside. They make great fertilizer!