The N-Ferno 6990 Hand Warmer Packs are long lasting and air-activated, instantly delivering up to 12 hours of heat. They’re great for placing in your jacket pockets, gloves or other warming accessories. Once activated, place the long lasting hand warmer inside a pocket or gloves. They’re also easy to insert into built-in pockets in thermal accessories such as the N-Ferno 6980 Hand Warmer Muff, N-Ferno Hard Hat Liners or ProFlex 825WP Winter Work Gloves. HOW TO ACTIVATE