HOW IT WORKS: The Ravelco key-plug is inserted into the Ravelco base just like a cigarette lighter. A hidden armored steel cable protects the wires from the back of the Ravelco base on through to the engine compartment where all the connections are made and camouflaged in the engine compartment. The circuits interrupted by the Ravelco device in the engine compartment may vary, but typically they include the electronic fuel pump, the ignition circuit, the starter circuit or the computer. When the 16 pin key-plug is removed from the Ravelco base it is impossible to start the vehicle. The Ravelco key-plug has over 100,000 different pin combinations vs. competitors who usually have only 6 different pin combinations. The product's quality and performance is far superior, which is probably why these devices receive such stellar reviews and have been sold since 1976.