N-Ferno® Full foot warming pack with self-contained to add heat anywhere when exposed to air. All natural ingredients heat up when they contact oxygen. Seal from oxygen in Zip-Loc bag and reuse the next day. Foot style warms up to 7 hours. For construction, freight or baggage, drilling or mining, oil or gas refining, iron or steel work, delivery or service, landscaping or grounds, cold storage or warehousing and material handling applications.