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. The mount comes with the LM-801-EXP-1 and LM-1001-EXP. The LM-801EXP has a 4 hole amps patern which will match 2 of the holes in the remote head bracket that came with your Yaesu remote YSK kit
Please note the Yeasu remote YSK kits do not come with this mounting package. You will need to purchase them from a Yaesu dealer.