In the Vendor Area at Defcon, you can find almost anything for sale, as long as it would be marketable to tinfoil hat wearers. These types of ex-military "seismic sensors" are buried around secret installations to alert security guards about intrusions. Now, you can buy them for your farmhouse for a thousand bucks a set.

In the Vendor Area at Defcon, you can find almost anything for sale, as long as it would be marketable to tinfoil hat wearers. These types of ex-military "seismic sensors" are buried around secret installations to alert security guards about intrusions. Now, you can buy them for your farmhouse for a thousand bucks a set.