This is the bottom view of the Laird MABO NMO mobile antenna mount.
In the center is the pin which connects to the coaxial cable inner conductor. The shield of the coax lays to the side and is clamped in place by the crimp tabs.
The foot covers the entire hole providing a good secure wide area to transfer forces with. This stronger technique comes at the cost of outside in installation as the piece shown must be installed from inside the vehicle. The two tips, and their pointy teeth, make part, if not most, of the electrical connection between shield and vehicle.
