Every time you press the button, the code rolls on to another of 14 million options, eliminating the chances of anyone "hacking in". We use 433 Mhz frequency, which avoids powerful emergency services signals from interfering. You can also operate the door from the receiver unit inside the garage. Can be operated from a minimum of 30 metres away. Maximum range depends on area Each transmitter is equipped with 4 channels so that other doors or products such as awnings or lighting can be operated from the same button. As it is radio wave controlled, it will operate from your car or from inside your house.