Hmmm... Well, survival mirrors such as the very popular StarFlash mirror have a special feature that you won't find on regular mirrors : an aiming aid.
It is very precise and once you've tried one, you will want to buy one. I demonstrated how it works to my father the day I bought mine and he was impressed that in less than one second, I could aim the reflection of the ceiling light into his eyes. It's really amazing. This is what I want in a survival situation : you simply wiggle the mirror a little bit while aiming at an oncoming aircraft, that should get you out of trouble. <img src="/images/graemlins/smile.gif" alt="" />
I wouldn't settle for anything less (ex.: CD-ROM) in a hiking backpack or survival kit.
P.S. : This is the mirror that's included in Doug Ritter's commercially available PSK.
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"The only easy day was yesterday."