UKC

It sounds as if a hiker has been found because he was wearing a bracelet which shows that he had stopped moving:

https://www.bbc.co.uk/news/articles/cq5jr0wlj22o

Sadly found dead. But what would this be? I wasn't aware that such a thing existed. 

A quick search will reveal all. Often used for kids or elderly family members with Alzheimer’s. 

I did a search for "tracker bracelet for hikers" and not much came up. I suppose it's not that different to the SPOT device which I own (although I never set that up to give notifications of my location continuously for fear of draining the batteries). But I'm surprised that these GPS devices for children and the elderly don't seem to be marketed to hikers more, as they seem a lot cheaper than the devices like the SPOT ones.