Hand Held Transmitter. See below

Without going all "Techie," the F channel encompasses a wide range of tuning frequencies. Like garage door openers, each time the remote is pressed, it causes the receiver to react based on the last transmitted frequency. Both units change to a new frequency in the F channel and re-set. Engineers take a lot of steps to ensure their wireless devices play well with others.

It's loke finding a "keyed-alike" lockset for several door. You have to go to the Lowe's store and look at aech package. Or, you can use thephone or the internet and waste a lot of time trying to get the same info.