I have had this Jon-E GI hand warmer for a few years. I received it from my father that had quit hunting due to age quite a few years ago. Decided to test it out and see how it does for a possible hand warmer during cold weather hunting season. It uses lighter fluid as the heat source. Works well. Temp climbed well over a hundred degrees F at one point. I did notice lighter fluid smell coming from the top of the warmer so I don’t know how well this would work trying to be stealthy while hunting or if deer would even care. I bow and muzzleloader hunt so I am usually fairly close to the animal while bow hunting and well within scent range. I know Zippo makes these and an electronic one also. Much more heat than the chemical ones. Started this warmer up at about 9:30 am and it just started to cool down at 5:30 pm. About 8 hours of warming time. You can see the catalytic material is red hot. Tested it for two hours and still going strong.