24 HOURS OF COMFORTABLE, CONTROLLABLE HEAT FOR YOUR SLEEPING BAG Need lots of heat fast? Remove, shake, and enjoy our industry leading heat output that provides safe, comfortable, natural heat when and where you need it, starting in about 5 minutes. The more air you give it, the more heat it can make. Need heat longer? Remove the warmer, shake it, and put it back in its pouch. The warmer will last all day. They are compact, convenient, and portable. You can even save one for later in the resealable, reusable temperature regulation envelope. How it works: They are simple to use. Open the bag, take out a warmer and give it a shake. The air will activate the warming agents and in 5-10 minutes the warmer will be giving off a nice heat. Put a warmer in your sleeping bag and it will stay warm. Our safe, natural air-activated warmer keeps your warm even in extreme cold. 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! Specifications for Ignik 24-Hour XL Warmers: Application: Outdoor Size: 4 x 5 in Fabric/Material: Vermiculite, Natural Materials, Salt, Iron Seasonal/Temperature Use: Cold Weather Weight: 136 g, 0.3 lb Heat Duration: 24 hours Features of Ignik 24-Hour Biodegradable Sleeping Bag Warmers w/Reusable AirBarrier Bags Safe, comfortable, air-activated warmer made from natural ingredients. Contains (2) 24-Hour warmers, one for your feet and one for your torso. Patent-pending temperature regulation envelope lets you save one for the next day, or use partially then re-seal and save for the next night. 98% Biodegradable. Contents can be composted after use.