Rating: 2 / 5
Keep in mind my comments are given in context of backpacking and challenge the notion that these tablets are suitable for boiling small water volumes, a claim found on the Internet here and there by hikers and retailers looking for a cheap Esbit alternative.
These things are as close as you can get to absolute junk, when it comes to selecting solid fuel for a lightweight backpacking cook kit where you need to boil 2 cups of water at a go.
The attraction is that they are extremely CHEAP. You can shop around and get 5 oz of fuel for a buck. The saying, "you get what you pay for" doesn't ring more true. After a week of using these on a trek, Mick was singing "you can't always get what you want" round and round my head. What I wanted was a simple cup of boiling friggen' water for a cup of Joe in the morning. It didn't happen.
Consider the water boiling capacity of a 0.5 oz piece of these tablets around 8-12 ounces in optimal conditions.
Upsides: they light easily and are available in about any 'army-navy' type supply store in the country.
Downsides: they burn way too fast - which results in massive amounts of heat wasted, and the tablet petering out before your mug of water boils. Granted: these were designed to quickly warm meals (MRE components), not boil water, so I've bumped my early rating up a notch as a charity point, after reading the next review below, which is a very fair one.