The product makes gooseneck microphones go wireless and installation a simple work. The ST-850 is compatible with PT-900B, PT-850B, PT-920B (G), PT-950B and PT-990B transmitter. The product works with transmitter’s power. When transmitters are unavailable simply connect the ST-850 to a microphone cable with phantom power. It works as a normal gooseneck microphone. Automatic wired/wireless mode transformation; no switch is needed.