Kozy 7800mAh Rechargeable Hand Warmer provides Comfortable, Soothing Warmth for Hours, Includes Bonus Warmer Pouch, USB Charger/Power Bank, and LED Flashlight & Emergency SOS, Full 1-Year Warranty

First let me say this is a great product and has been a wonderful tool in assisting with keeping circulation to my fingers due to Raynaud's. Now for the good and the bad. I ordered one unit to check performance planning on ordering a second unit if the first proved helpful. The first unit I received appeared re-packaged. The film covering the control panel was wrinkled appearing to be reapplied, the insert in the box was bent and more telling the instructions stated "IMPORTANT" unit must be charged before using. To plug in and the three LED lights would start to flash then move to a flashing sequence until fully charged when all three blue LED lights would glow continuously but when the unit was connected to the charger all the lights were already glowing and showed fully changed, hmmmm! I let the unit charge overnight anyway and was somewhat pleased with the performance the next day. A recharge and another day and the unit was warm but would turn cool when held in my hand. Hoping against hope and believing that I had received a returned unit with faith a second unit was ordered. The second unit came uncharged, all packing material looked original and it worked wonderfully. If kept my hands warm even while holding it. The high setting while in my slack pockets proved to be too hot against my thighs and needed turned to low; the low setting works well and supplies enough heat to keep my hands comfortable or to assist with maintaining core temperature when my hands are not in my pockets. The charge on low last for between 8 and 9 hours. Other reviewers have reported greater lengths of use but I am finding the run time has expanded after additional charges. Today I will contact Amazon about replacing the first unit and plan to use these for years to come figuring on ordering new units every two years or so since I will not have to use these during the summer when it is warmer unless finding myself in extreme air conditioning. I may even order another set (total of four) for use while hiking in early spring and late fall in cool climates. These are used in the house and throughout the day to keep circulation in my fingers and are so much better than the chemical packs that we purchased in cases from warehouse stores before this.Concerning the second unit. Received aa email from Komfort Solutions after the return was requested. Meg at Komfort Solutions seemed very concerned about the performance of their product and was interested in the reason for the return. After exchanging emails I could tell that they were already working with Amazon to check on how a possible repackaged unit could be sent. The second unit that I purchased as noted in the review above works exceptionally well and I had planned on ordering a replacement for the first unit once the return credit was applied. Komfort send a deeply discounted code to use to assist with the replacement product, they do stand behind their products. I plan on ordering a second set for the long winter hikes with my wife that I have had to curtail due to the progression of the Raynaud's. I have found the units good for 8-9 hours of use on the non-high setting but the time seems to be expanding with each charge; I just want to make sure there is enough power to handle an entire awake day before the next harsh winter reappears.

The unit does get warm as advertised, but it is not as big as it appears in the photos. It's 2.5 inches wide, 3.5 inches tall and 1 inch deep. I have small hands and it just fits in my palm. The aluminum scratches very easily as noted in the photo and I've only had it a few hours.

Received 2 of them today. Each got to a full charge either in 2 or 3 hours max. For me, they're too hot on high, but I believe that would be a plus in extremely cold weather. The lower setting is very warm. These things will definitely keep cold hands warm in cold weather. Turn it on, and you begin to feel heat in about 5 seconds. In 20 seconds, it will be warm enough to warm your hands. The flashlight is extremely bright. Tried it in a totally dark room. What a wonderful product. Can't wait to give as Christmas gifts. I hope in the future the company makes them with batteries that can be replaced. To have to throw these things into recycle is a waste. I looked up the type of battery used (3 ea. 18650-Li ion) and Amazon sells them. They appear to be the size of AA batteries.Update 12/31/2015: bought 4. Returned one yesterday. It fully charged when first charged; however the 2nd time it would not, even overnight. I had the warmer on the lower setting, and the temperature did not seem to be constant. It would become much warmer, more as if it were on the higher setting, and then it would drop to feeling less warm than when on the lower setting. I hope the others aren't like this. Three were Christmas gifts.Update 1/6/2016: I returned one and rec'd another. Today I tested the replacement to see how long the heat lasted on the lower setting. What a disappointment! It was fully charged, and it was done heating after about 5 hours & 15 minutes. This is at least 3 hours less than stated in the description. I don't know if I rec'd a unit with older batteries that were past their prime or what the reason could be. Two of the units of the 4 I bought were for someone who will be traveling in a cold climate, and I wanted this person to have a heat source, should he be stuck in a snowbank, for example, waiting for help. They are good and certainly provide enough heat, but I am disappointed the heat quit so soon.

For a long time, I would grip cups of hot water to warm my hands, which was inconvenient logistically. This heats in about 15 seconds, far quicker than I would have guessed. This is a great replacement for hot water, though there are ways it could be better. I use the high and low heat settings at different times. The shape is comfortable to grip. I use it for much of the workday, perhaps 6 hours of use. I primarily charge it overnight. The battery usually doesn't last me all day, and it barely helps to charge at lunch and when my hands aren't cold. Plugging it in to charge automatically turns it off; in fact, this is a convenient way to turn it off.No wall charger was included, so I charge by connecting it via USB to a desktop computer. Perhaps the right charger would allow it to charge more quickly. I plan to make that a non-problem by purchasing a second device.To turn it on or off, you hold the button for several seconds. This is a awkward. I'd prefer something quicker, like a double button tap.