The link to camp Canada had the most common methods. Most of us on this list will never have to resort to that because we will have one (or two) with us. The waist belt on my every day around town bag, hiking, climbing bag has a full-blown Suunto MC-1G mounted on it all the time with a Silva type #27 living in my FAK both have mirrors on them for sighting and signaling etc.
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When the wolf attacks he will find that some who run with the flock are not sheep!