Emergency Survival Whistle. Orange.
This is definitely an essential piece of any survival kit and a must to keep around your person when out and about walking, fishing, boating etc. A basic (no moving parts to go wrong) high-pitched and high visibility whistle which floats on water and, in an emergency, could turn out to be the best quid (or thereabouts..) you've ever spent! Simply blow hard, and for an SOS (internationally recognised distress signal) situation - three short blasts followed by three long blasts and then three short blasts again. Repeat.
We even put them on a little lanyard to secure to your clothing, ideally inside of an easy-reach pocket.