4 Bolt Flange Mount 1/2" Bolt Holes 3/16" Thick Steel (Fits 1 1/2" Sq. Tubing) $ 5.00 Qty: Add to Cart Tube Flange Mount: Material Type: Mild Steel Fits 1 1/2" Square Tubing Material Thickness: 3/16" Bolt Hole Diameter: 1/2" Length: 3 1/2" Width: 3 1/2" 1 1/2" Square is oversize by .050 for fitment and welding.