The Stethophon® 04 is an acoustic detector for displaying and amplifying structure-borne oscillations of all kinds. The oscillation sensor provides undistorted sound reproduction even when the noise is barely audible. Besides the cable headphones, a wireless version is available including SDR (Sewerin Digital Radio). The SDR offers a sound transmission quality equal to or better than cable. By going without the cable, the comfort of work is improved considerably. Headphones and detectors connect automatically by bidirectional radio link when switched on.