VHF antenna bracket

This is part of the initial design of a bracket to hold a VHF antenna. The bracket will be rail mounted, the diameter of the rail being 19mm. The bracket is in two parts. Other parts are required to complete the unit, these were sourced from an existing mount.
A picture of the existing style of mount is included.
On fitting the unit other improvements have been noted:-
The holes on the lower section could be changed to hex shape to accommodate nuts without them turning. At the time of des