I had previously ordered a box of the 10 hour hand warmers, but I read the reviews of the 7 hour warmers and ordered these when I ran out. I wish I'd ordered the 10 hour warmers. It's cold here in Cortez, CO and the 10 hour warmers really pack a punch. We had to use 2 of the 7 hour to achieve the same warmth. So, if you live in a cold place, get the 10 hour warmers!