· The MX393: a surface-mounted microphone; includes a programmable membrane on / off switch · an on / off indicator LED · and a miniature · three pin connector. Microflex Wired Boundary Microphones from Shure are the smartest boundary microphones yet. Equipped with features like programmable · silent membrane switches · logic inputs and outputs · and LED indicators · Microflex Boundary microphones are the high-quality solution for a range of applications · such as altars · boardrooms and distance learning centers.