Works great hot heat warms my Raynauds syndrome up.

Works great hot heat warms my Raynauds syndrome up.  Read Less

Another Raynaud's Syndrome person here, ugh. What an annoying condition. My fingers can go from warm and pink to ice cold, whit...  Read More

Another Raynaud's Syndrome person here, ugh. What an annoying condition. My fingers can go from warm and pink to ice cold, white, and numb in a matter of 5-10 seconds in the winter - even just getting ice cubes out of the freezer. Needless to say, I've been through a lot of hand warming products over the years, everything from down mittens to chemical hand warmers, etc.I really, really like the USB rechargeable batter hand warmers in general, and of them (I've owned 6) this is one of my favorites.Pros (relative to other USB hand warmers only):- the heat is very strong - blistering, actually, if it's fully heated up and you're just grabbing it. I haven't temperature tested it with a thermometer or anything, but I can tell you that if most of them get hot but not very hot, this one is super-hot. In fact, so hot it can be hard to hold, which is mostly a good thing, because you can always let go of it for a minute if it's too hot, but you can't make it hotter if it just ain't hot enough. I have not encountered any other USB hand warmer that puts out this much perceived heat. Seriously, you could probably cook an egg or a grill cheese sandwich on this thing.- auto shut off is a handy feature. Seems to go off automatically after an hour. Really like this feature- the battery is bigger than some of the others (though not all of them) - 7500mAh vs typically 4400ish. And this is a case where bigger is better. Bigger batteries last longer, obviously. This pumps out its ridiculous amount of heat for a good, solid 2.5 - 3 hours, compared to the 45 mins - 1.5 hrs of some others. By the way, don't believe the claims either of this or any other USB hand warmer. NONE of them last the advertised 6-8 hours, period. Trust me, I have been around the block with these devices and those claims are ridiculous. Getting a solid 2+ hours of heat out of one of these is victory, and this one delivers. Don't be surprised if you buy one of the 3600-4400mAh models and get 45 minutes of heat, that's just how it is. Also, if you're going to use it for back-up phone charging, you're not going to charge a phone effectively with 3600-4400mAh; you really need this (or comparably large battery) to do that.- though a bit larger or thicker than some of the others, it's actually a very comfortable, ergonomic shape for wrapping your whole hand around and getting all five fingers on the heat. Don't be seduced by those little ones that look like they're just slide right into your pocket and be out of the way!! They do in fact do that, but they don't have either the large heating surface or the longevity of this unit. A large heating surface is very important with these things. The part making contact with your skin loses its perceived heat in a minute or two; only the part you're not touching stays scorching hot. With such a large 2-sided heated area on this unit, just turning it over in your hand will exposed your palm and fingers to a fresh section that will be very, very hot. Meanwhile, the used up cooled-off parts you were holding before will go back to blisteringly hot in about 30 seconds. Not many (or any) other hand warmers have this much surface area and can constantly give you virgin areas to apply high heat to your hand continuously.Con:- Quite unusually for this type of product, it has no low vs high switch. When you turn it on, you're getting the full blast of heat. It's odd that it doesn't have this functionality since almost all of them do. Not really a big deal, but to be clear this one pumps out a LOT of heat and it can in fact get too hot, so hot you have to remove your hand, whereas with most others you can just kick it down to the low setting. This unit with a hi/lo switch would definitely be my favorite device in its category, but unfortunately that is not offered (yet).Given its high heat level and lack of option to tamp down the heat level with a hi/lo switch, it's suited mainly to outdoor use in the winter, where its high heat and large heated surface area provide distinct competitive advantages. For indoor use only, I might recommend one with a hi-low switch, really any of the ones with 7500+mAh would be suitable for that purpose. I do use it indoors but sometimes it does seem too hot to me and I have to turn it off and give my hands a break for a while.On the upside, one thing people complain about with USB hand warmers is that they're not hot enough. Trust me, you'll never have that complaint with this model.I feel that in this product the manufacturer has what could potentially be the best USB hand warmer on the market, but it really needs a hi/lo switch. I'm still giving it 5 stars, because of its combination of ergonomics, high heat level, longevity, simplicity, etc. But it needs a hi/lo switch.  Read Less