I find them easy to carry in the wallet and they DO start a fire, but I found it "touchy" in getting the sunlight into that nice round beam of light. It's kinda squarish and I don't think it is as hot and quick as a regualr mag glass lens (although, it lit my char cloth instantly and from that, I was able to easily get a fire going.)
Michael
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That which does not kill me has made a grave tactical error.