I keep these rechargeable hand warmers in my coat pockets at all times. I'm not kidding when I say they heat up in 2 seconds - all the way up to 131°F (they have 3 different temp settings). The charge lasts for 20 hours so I really only charge them once a week. They're super handy for winter walks, errands in the city, and chilly sporting events. They come in 6 different color options too!