If they are the same ones I bought a while ago from CC a while ago, neat toys, smaller than a dime. I would not depend upon them to be seen from very far or as a replacement for a true survival strobe. They may have a greater distance of observance on a very very dark night or if night vision devices are being used in the search. They are the same LED flashers that are sold as novelty items that teens use at raves for bellybuttons and clothing.

Pete