The Diamond K-400 is a heavy duty antenna mount made for large VHF/UHF antennas and medium-sized HF antennas. It is one of the strongest antenna mounts made today. It has two-axis adjustment that will allow you to position the antenna in just about any position. It has 4 set-screws that allow strong no-hole installation.
I have two of these mounts. One holds my Yaesu ATAS-120A and has done so for going on 5 years now. I drive 40 miles to work and this mount has held my ATAS at highway speeds this whole time. Before the ATAS, this mount supported a Diamonf HV7A for about 5 years. My other mount has held an MFJ-1432 antenna for a few years now.
I check the mounts monthly to look for cracks or loose fittings, and tighten them about every 6 months. So far I have had no problems with my K-400 mounts. This is a very reliable mount and worth every penny if you have a heavy antenna.