Having electronic signaling devices isn't the end of the story; you need to consider whether your gee-whiz electronic device might fail for any reason. That's where these come in. Whistles carry far louder than voice, and two minutes leaning how to use a signal mirror can enable you to signal potential rescuers many miles away. Additionally, marking your site is vital. Survivors can become easily lost while gathering firewood or checking snares, for example, and rescuers need to be able to find you if you happen to be sleeping in your shelter.