Apple Daily reports the eavesdropping devices were originally installed under the name "inspection and quarantine cards” back in July 2007. The Inspection and Quarantine Bureau installed the devices free of charge to thousands of vehicles across Hong Kong. The devices are about the size of a PDA, screwed into the car’s front .
People in Hong Kong, in particular criminals, began to notice something was awry when the authorities were able to pick out cars carrying illegal goods across borders without problem or hesitation.
"For every ten cars we ran we only had [smuggled goods] in three or four to reduce the risk, but the border agents caught all of them. The accuracy was unreal!" one smuggler told Apple Daily.