no real world myself but the are widely discused at a camp
stove site..used by the new zealand army in ww 2 and by fisherman in england in the 1900's..if you want lots of hot water
they are said to be really worth it..another company, Thermitte- not sure of the spelling--makes one with a handle on
the side that is said to be easy to use as you don't have to fool with the chain to pour..