Ideal for cold weather work and recreation, N-Ferno Warming Packs heat up in seconds and provide continuous warmth. The self-contained packs add heat anywhere when exposed to air. To activate, simply open the pack. All-natural ingredients heat up when they contact oxygen. Seal from oxygen in Zip-Loc bag and reuse the next day. Environmentally friendly hand warmers keep your hands warm up to 8 hours. They are great for construction, freight/baggage, drilling/mining, oil/gas refining, iron/steel work, delivery/service, landscaping/grounds, cold storage/warehousing and material handling

We stand behind everything we make and guarantee our products to be free of defects in materials and workmanship to the original purchaser for the lifetime of the product. That said, damage, abuse, and/or normal wear are not covered. (Don't lawyers bring you down?)