The 545SD-LC Classic Unidyne Instrument Microphone from Shure features a dual-impedance, unidirectional, dynamic configuration. It is designed for instrument pickup and recording and can be used on lecterns for public address systems, such as those used in political conventions and legislatures, convention halls, hotels, public auditoriums, stadiums, schools, and churches. The microphone comes connected for low-impedance operation and features a silent magnetic reed on/off switch.