The Model 515BSLX is a dynamic (moving coil), low-impedance, cardioid (unidirectional) microphone designed for mounting on a gooseneck or fixed pipe with a 5/8 in.–27 thread. The cardioid pickup pattern provides excellent voice reproduction with effective rejection of feedback and background noise. The 515BSLX is especially suitable for use in communications, paging, and talkback systems. The microphone is supplied with a slide switch controlling the microphone audio and a relay circuit, permitting hands-free operation. The microphone comes with a 1.8 m (6 ft) four-conductor, two conductors shielded, cable. The 515BSLX is wired with the microphone circuit normally open for use in parallel-wired microphone installations.