I'm not so sure; the RECCO system has a 200 meter range in air, 30 meters in snow, shorter in wet snow -- but that 200 meter range says that it may have other uses (still thinking). Neat technology though -- no moving parts, no batteries to die/change, just a tuned cavity that responds to the RECCO detector and reflects a signal back. Whatever, they're embedded in the pants and per the website video the reflector requires no maintenance and has an unlimited lifespan.

Not affiliated with RECCO, just interested in elegant yet simple to use technology.