I carry a hot spark on my keys as well... I just love the little guy.

I showed up for some winter camping at a scout camp a bit earlier than the rest of the troop. I didn't have a lighter or matches on me, but I was able to get the wood stove going with the hot spark and some tinder that I always keep in my coat.
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"I reject your reality and substitute my own..." - Adam Savage / Mythbusters