Most of the cars manufactured in the last 20 years have transponder keys as part of their anti-theft security measures. Transponder devices use microchips to transmit a low-level signal from a key read by the remote receiver. The microchip shall be programmed by a manufacturer with a specific serial number. Using RFID ( Radio Frequency Identification), the receiver must detect the appropriate serial number for unlocking or opening. Similar to key fobs, transponder keys are often used with car locks and home security systems as well as to open doors and garage doors. In the case of car transponder keys, when the key is inserted, the signal is sent to the receiver located near the ignition. If the digital serial number in the transponder matches the one in the car, it will start when the driver turns the key.