i bought it in austria, go on orthovox page and y ll find it, i tested them both, mammut is better, transmitter is ortovox- i put it on collar on my own, make a small plastic protection. all transmitters, boxes work on the same frequency 457 so they will work together, but first of all BF wont sell y just the collar, i spoke with them several times, i also asked them if their collar d work with mammut, they confirmed it, but they spoke about some special software in their box/ wich is Pieps DSP/ just think what is more important, dogs or humans? so can be dogs locators better than those for us