I grew up in the Chicago area, and our weather can be notoriously extreme. We get some ridiculously hot and humid summers, then winters which are so often brutal that when a day rolls around where it's "only" 40º F out we'll be wandering around outside in t-shirts like it's the middle of summer. Once I discovered chemical hand warmers like these, I pretty much always carried a pair in my coat pocket ready to deploy when the windchill gets too severe. The problem with chemical hand warmers is even when you buy them in bulk they're around a buck a pair, and there's a major psychological barrier to actually using them since they're consumable. It's kind of like how you can play through an RPG conserving health potions so much that by the time you beat it you've got a massive stockpile you could've used the whole time. A few years ago I discovered Zippo Hand Warmers, and they've been a total game changer. For a few cents worth of Zippo fluid you get hours of warmth- Zippo says up to 12 in total, if you've got the larger of their two hand warmers and you fill it all the way, although I'm fairly certain I've gotten more than that. Their traditional hand warmers come in two varieties: A 12 hour model, and the significantly smaller 6 hour model. Amusingly enough, as of this writing they're about the same price with the 12 hour version selling for $12 while the 6 hour version sells for $13. The way these things work is they come with a little measuring cup thing that yo...