Fuel-based hand warmers?

I'm looking for the best option for hand warmers and wonder if anyone has experience with the fuel-based hand warmers like Zippos? Or are the throw-away kind better?

Throw aways are better. No scent from them like the zippo type.

I have an old Zippo my dad used to use and it will flat burn you up; as a matter of fact, I believe it would keep a small room or tent warm when fired up. As for the scent, hunt downwind.

correct on the downwind.

Too much smell on fuel heat--especially bow hunting. Now if you're in some giant tower blind , go for it.