The units are tiny as you can see from the photos attached coupled with a 1 pound coin.   You basically need to stick a small piece of velcro on the transmitter and place it under your detector shaft  with another piece of velcro somewhere near to your headphone socket so as to be able to plug in.  The receiver can be placed in a pocket once paired with the transmitter and then you have the ability to plug any wired ( shorter cable the better) headphones of your choice into it.