With the price, size and weight going down over the last few years and the technology going up, we are continually getting asked more and more about Personal Locator Beacons (PLB's). Once upon a time the only people we would see carrying a PLB were guides or climbing and bushwalking clubs that banded together to get one to loan out to their members. These days however many weekend adventurers, climbers, trail runners, walkers or travelers are taking them out with the view of it being a relatively well priced insurance policy.
The size too has been a huge factor in its increase in popularity. Personally a couple of years ago I wouldn't have dreamed of taking a radio style PLB on an overseas alpine climbing trip because that wasn't in my 'fast and light' (or at least that's what I told myself) ethos, let alone a rock climbing trip. However now on my trips to New Zealand, one stays in the lid of my pack with the hope that my wife sleeps better at night.
Below is a great video (part 1.) by ACR who manufacture the ResQLink PLB as to why, if you're after a true rescue device, PLB's are the best way to go. Products like satellite phones and GPS trackers (ie. SPOT) are great for their intended purpose, but when it really comes down to calling in a rescue nothing can be more reliable than a PLB.
For more information on the ACR ResQLink click HERE