Advanced Tactical Security & Communications Ltd (ATSC) makes the ADE 651. It can find guns, ammunition, drugs, truffles, human bodies and even contraband ivory at distances up to a kilometer, underground, through walls, underwater or even from airplanes three miles high. It didn’t even need batteries — it was powered by “electrostatic magnetic ion attraction.”
Except that it was a complete and utter fraud.
Modern day hokum version of a dowsing rod.
Recall reading articles in "Skeptical Inquirer" about this device and similar ones.