Bits and Pieces - Flame Handwarmers - Reusable Fast-Acting Hand Warmers - Set of 2, Each Measuring 3-3/4" Long - Stocking Stuffer Gift These amazing little pouches heat up instantly to provide you with a pocket full of warmth. Simply give the internal metal disk a few bending clicks. This activates a chemical reaction that causes the liquid to crystallize and heat up to approximately 130 degrees. The packs will stay warm for hours if placed within a pocket or gloves. Use them time and time again. Set of two hand warmers each measuring 3-3/4" long.