Transponders are hidden inside the molded top of the key. In simplest terms it’s a radio transmitter/receiver device that is programmed into the computer of the car. If the corresponding key to the computer is not used on the car, the car will not start. Losing transponder keys is a major problem if no spare keys are available. Some cars require the actual Engine Computer Module to be replaced, making it an extremely expensive adventure. A spare key could save you thousands. Our car locksmiths in Hummer are equipped with all the computer programming equipment needed to duplicate your keys accurately, while you wait.