Zippo Hand Warmers: http://amzn.to/2sgKGqh
HotHands Hand Warmers: http://amzn.to/2nPzVpl
I have tested the standard hothands 10 hour hand warmers vs the zippo 12 hour hand warmers. The hothands are the standard air activated style handwarmers, like the grabber mycoal brand. The zippo uses zippo lighter fluid or zippo handwarmer fluid. Zippo handwarmers are reusable, where the hothands are a one time use. The cost per use is relatively close between the two handwarmers, but the performance is very different! It was very interesting to see how different the two brands and styles were.