A simpler version of the smart key system is the engine immobiliser, involving a security key system embedded into most modern vehicle's keys. A small chip rests on the vehicle's key or under the plastic key cover. When any key is inserted into the ignition, the ignition is coded. The key sends its security code to the ignition, which also has its own security code, and if the security codes match, the vehicle will start when the key is turned. However, if the key codes do NOT match, the vehicle will NOT start when the key is turned. Some early examples of this technology include Chrysler Corporation's Sentry Key System, or General Motors's PASSKey System.