Q: Will this work with the Vertex Standard VXA 300? if not, what will?
A: No, this will not work with the VXA 300. You will need the Vertex CT-96 Headset Adapter.
Q: Will this work for the Vxa-220 Standard?
A: Yes, this will also work with the Vertex Standard VXA-220.
Q: Is the Vertex CT-60 Headset adapter compatible with the VXA-700 transceiver?
A: No, the VXA-700 and Vertex VXA-710 Transceivers require the CT-96 Headset Adapter found here.
Q: What are the sizes of the 2 female plugs?
A: The 2 female plugs are fixed wing/general aviation plugs and are 6.35mm and 5.25mm.