In these days of high tech gear one of the best is the whistle. It’s cheap and light and may save your life. In many years of mountain rescue we located many casualties by their whistles.
When I climbed a lot we also did a few rescues of crag-fast folk. This is where the whistle was handy and we carried one on our harness a good tip?

I had the same one you pictured attached to my lifejacket for kayaking in the US. It was actually a law: ” Every vessel less than 65.6 ft. (20 meters) in length must carry an efficient sound producing device.” When hiking I had one on a cord round my neck; sometimes you’ll wander for a bit without backpack.
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Good point
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