Gary Bolton, 47, of Kent, England, was convicted of fraud for making the unreliable devices, based on a novelty golf ball finder, and selling them from 2005 to 2009 to military and police clients in countries including Mexico, Thailand, Pakistan and China.
The devices cost less than two pounds ($3.13) to manufacture and were sold for up to 15,000 pounds ($23,502) each. Bolton earned 3 million pounds ($4,700,580) per year from their sale, the British newspaper The Guardian reported.
Human rights campaigners in Thailand identified two bombings that killed four people after the device was used to check suspicious vehicles.
The sentencing judge, Justice Richard Hone, pointed out the flawed detectors "did materially increase the risk of personal injury and death," and noted Bolton "damaged the reputation of British trade abroad."
Bolton's sentence follows a 10-year sentence given in May to his former business partner, Jim McCormick, for selling about 50 million pounds ($78,343,013) of similar devices, many to postwar Iraq, the newspaper said.