At first they looked kind of gimmicky or I'd say... artificial to me but since Doug reserves a place for them in his cold weather survival kits as well as many others in this forum like Frenchy and knowing how room is at a premium in a survival kit, I figured they must be efficient.

So does anybody know by any chance how Heat Factory handwarmers compare to Grabber Mycoal handwarmers?

http://www.grabberwarmers.com/index.htm
http://www.heatfactory.com/index.html

Heat Factory, situated in Canada, claims they are the oldest handwarmer company in North America. (founded in 1980)

According to Grabber Mycoal though, the original idea is from Japan.

Anyhow, what really count is to know which brand is the most performant. They are probably very similar but I'm asking anyway. I've never bought and tried them. I will consider them next time I visit outdoor stores and pharmacies. Since they are inexpensive, I will try to buy both brands and test them for myself but I'm curious to know your opinions. I also get a kick out of reading replies sometimes.

Thanks
François