Car Spark Plug Concealer – A Discreet Solution for Hiding Recording Devices and Small Items Overview The Car Spark Plug Concealer is a discreet and effective solution for hiding small recording devices, memory cards, USB drives, cash, coins, jewelry, small medications and other personal items inside an innocuous-looking everyday object. The simulated spark plug looks and functions like a standard car spark plug, but inside it hides a hidden storage compartment that allows you to hide sensitive items without arousing suspicion.