Warmth This snack-bar-size DryGuy gadget warms up to an average of 1150F (a few degrees more than other, disposable hand warmers), acting like a tiny, four-hour furnace for our fingers. It’s better for quickly warming chilled hands than for all-day heat.
Power Use it to charge your phone twice.
Sustainability Although it doesn’t fit in your glove a well as a single-use hand warmer, it also doesn’t end up in the trash after each use. Our gear editor used one all winter with only a slight loss in charge retention.