The base of this mount expands out to 3 3/4 inches in diameter by turning the adjusting knob. The neck of the mount is flexible so you can adjust the mount for the perfect view of your device.
This mount comes with the EXT-01 extension bracket with the LM-1203 microphone holder attached and a 5mm bolt that you can thread right into your control head. Your control head has a 5mm threaded hole that the bolt can be attached direclty to. Nothing else to buy..Good Job Yaesu.