This a great alternative to Icom's mouning system for the ID-5100 or IC-2730A which consists of the MBA-2 and the MBF-1 that will set you back about $120.00.
The mount slides down into the cup holder and can be expanded for a snug fit by turning the tightening knob. It will expand out to 4 1/2" that will fit most cup holders. The kneck is flexible so you can adjust it for the best viewing angle.
The mount attaches directly to the Icom ID-5100 and IC-2730A control head with the screws that are included with the mounting kit.