I have used several of these-
Plusses
reusable
cheap
minuses
EASY TO BREAK- I try to be careful, but the plastic does not seem to last all that long- most of mine broke/leaked within a month.
Short they only release heat for 30-45 minutes. Enough to shovel, but not that long
storage They do not STAY liquid; whether mine just get bumped in storage, or they somehow age; I I left it and came back a few months later, they were all crystallized, and had to be heated to use-
Bad QC- when I bought them, I would buy 3 or 4 at a time- they never maintained temp the same between each batch-
Very helpful review, LCranston, thanks. It looks like these are not marketed for camping for a reason - not sturdy enough for a typical field abuse.
For the problems mentioned above:
- the Russian model seems to be better as it is able to generate heat for 2-4 hours (when used under clothing and in the sleeping bag).
- The plastic on those looks beige instead of blue, and holds well at -20 C (-4F)
- The noted spontaneous crystallization after prolonged storage time is typical for any saturated solution of salts. To prevent that you have to shake the solution periodically.
It looks like somewhat different brands to me.
Anyway, just ordered one for testing and in hope to improve some of its properties, because infinite reusability is really very appealing to me. Going to try ordering the Russian model to compare.