Nagoya RB-46 antenna mount
I have been using this mount for the whip antenna in my ham radio trolley and I couldn't be happier. When I bought mine long ago it said it was stainless steel, and the truth is that both the mount and the bolts look like that, but I couldn't assure that all on sale will be the same. The mounting system allows it to be mounted on horizontal or vertical rails, and orient them at a 45-degree angle too. It has a 16mm hole, which is good for an SO-239 or an insulated 3/8-24 or M10 bolt.