>> randy joins us now. you've been working with these beacons all day. how much water does it need be in before it starts pinging? >> reporter: they can survive in depths of 20,000 feet. what we want to show you tonight is how sensitive they are. we have this tin cup here. it has a moist paper towel in it. no water in it. this is one of the pingers. we have the tester right here. i'll be quiet for a moment as we put this in and just with a moisture paper towel listen to it activate right away. [ pinging sounds ] you hear that right away. it starts to work. we also want to tell you tonight we talked to the people here who make these and said we talked a lot about the 30 day deadline for the battery to run out because it only lasts 30 days. they said there's a three to five day grace period so that was good news we may have a few extra days. they talked about the fact --