This is interesting. The claim is that "The handheld detector can locate RECCO reflectors within a range up to 80 meters through air and 20 meters through packed snow".
It would be great to see someone with proper equipment try to go into technical details. Passive detector doing 20 meters though the snow seems crazy.
The better 58kHz store alarm (EAS) systems can detect tags at 4-5 m range to allow concealed installation at higher-end stores for example, and they have to respond very quickly with a low false alarm rate because you can't expect customers to stay still for many seconds while the detector gets a reading, and you don't want to unnecessarily bother a customer who just bought a $5k handkerchief. The tags are just passive high-Q resonators, some are coiled, some simple strips of magnetostrictive material.
Unlike shoplifters, avalanche victims can be expected to stay still, so you can realistically extend the detection time by one or maybe two orders of magnitude.
It might be impressive if they have miniaturized the reader and/or if it has a fast response time. Otherwise shouldn't be too hard if you allow yourself ginormous coils and a read time of say 1 minute.