Comments about Overton's Split Bracket, Fits 4" - 18" Rollers:
The slots are in metric I believe. So, 1/2" galvanized bolts don't fit. You cant get 7/16/" or metric galvanized bolts at most hardware stores. So, you'll have to grind the slots out to 1/2 inch to make them work. But, there doesn't seem to be any other choices.