Cable with rubber-sealed contact microphone in special housing which is electrically shielded. Means: no hum is introduced, only your crystal clear signal. Made for Microphonic Soundbox (which also is a ultra low noise high class amp with 40dB amplification), but you can use it with any mixer, interface, recorder. Usable as contact mic or pressure sensor for modulars. It is rubber coated but not waterproof (it might be, but was not meant as hydrophone).