Like the other poster said, it comes with a receiver you can use independently or inline with a door switch you already have. You can also buy just the transmitter (for about $30) and put them in your cages if they do not already have factory remotes in them. Then just tap the high beams and the door will open and close.
Pretty neat me thinks..

 

How did you get that price?

 

Call Eastern Performance. Ask for their best price. I try to buy 2 or 3 things at a time. Helps them save on shipping (free to you) and I have ALWAYS got a little better price than their advertised prices (which are pretty good). They sell these for $64.95..just asked nicely, they cut it to 59! They are Great to deal with and no tax and free ship!