I bought this sound tube designed for fire services. Sat him until recently even the Motorola GP900 FUG 11b (analog radio), and now the Motorola MTP850 (digital radio). The sound quality is for this application definitely good. But what struck me is that the black cable is only moderately expanding and therefore always has a larger train on it and the jack plug is a little loose. Next time I would probably try a different sound tube.