The eGear® Guardian™ is a small, wearable, LED Signal Light that is visible for over one mile. It can be clipped to a hat, a pack strap, or anywhere you want to signal your location. This light is dual function with both a steady-on and flashing mode. I have had one of these attached to the top of my pack with a Velcro strap for years. Just turn on the flashing mode and you can be easily observed from the air. To change mode from flashing to steady-on, just flip the battery over. Waterproof to 300 feet, the battery life is 250 hours in flashing mode and 100 hours in steady-on mode. Measures only 1-5/8" long x 1-1/4" wide x 1" high, and weighs only1 oz.