JulieBuehler wrote a review of Mammut Barryvox Opto 3000 Beacon on January 8, 2007
I was definitely impressed with this beacon. It is very compact and comfortable to wear all day while ripping up the back country. The best feature is that it allows you to test other beacons to make sure they are working. So not only can you be confident in your beacon, but you can trust that your buddy's is working too.