Product details:

Sold As A Set of (8)... Heavy Duty .40" Thick Aluminum... Clamps To Trailer Frame Using Base Mounting Bracket... Adjustable Vertical Mounting Holes For 1/2" Diameter Bolts ( Bolts Not included )... Vertical Bracket Measures 5" wide by 10" Height... Aluminum Construction... FASTENERS NOT INCLUDED... Other Brackets and Sizes Available...