Linear MCT-11 megacode garage door opener 318mhz megagcode (no dip switches to set) MegaCode transmitters and receivers do not contain a typical ""coding switch"". Each transmitter is permanently coded at the factory. The transmitter sends a unique code when the button is pressed. The receiver is programmed by learning a transmitter's unique digital code. The receiver will activate only from the memorized transmitters. It has a high visibility test/operate LED A spring-steel, dual-position visor clip that attaches vertically or horizontally. It measures 3.04-by-1.93-by-.61 inches. It is available for use with all Linear?s garage door openers. The transmitter is powered by two Type CR2032 coin-cell batteries.