First time filling and using a 6 hour and 12 hour zippo hand warmer. Temp Checks

3 hours on the 6 hour warmer
8 hours on the 12 hour warmer.
2ed fill up. I got
6 hours on 6 hour warmer
18 hours on the 12 hour warmer.
12 hour warmer was not very hot the first 6 hours but was good enough. then got really hot and lasted 18 hours total