Very sturdy clamp!
I am rather novice in actually building things, and wanted to clamp my mast to 4x4 post right. Stainless strips and some 2” screws did not feel right...
When the clamps first came, I was on the verge of returning them, since they would not snug 4x4 (nominal, 3.5” real) post at all, inner size was more like 4 3/4”. Still, was encouraged to just clamp them, and worked like charm!
Tidbit of info from another site: separate two clamps with 1-2 inches per foot of mast length (2 in windy areas) — would be nice if some advice like that be available here!