The Shure Model 515SDX is a dual-impedance, cardioid (unidirectional) dynamic microphone that is suitable for speech pickup in schools, churches, and meeting rooms. Its unidirectional polar pattern greatly reduces feedback. The 515SDX mic includes a locking ON/OFF switch and an internal impedance selection socket mounted on the XLR connector for switching between high and low impedance. A slip-in swivel adapter is supplied for stand-mounted use.