This is a new in commercial packaging Vertex MH-700D DTMF microphone.  Radios that use this item are the
VX-2000, VX-2500, VX-3000, VX-3200, VX-4100, VX-4200, FTL-1011, FTL-2011, FTL-7011, VXR-7000, and VXR-1000.  DTMF is Dual Tone Multi Frequency.  It has the RJ-45 male jack. Two are available at $50.00 apiece.