On 04/06/2021 13:48, Fredxx wrote:
What's wrong with studding, nuts and large washers? The fact there is a
square hole doesn't mean you have to use it.

The square shank under the head doesn't matter, roofing bolts would be
OK. I wanted a domed head to match the others. I'll order online as
people point out these can be had. Galvanized woud be nice, not BZP (ach
ptui!).