4 Bolt Flange Mount 3/8" Bolt Slots 3/16" Thick Steel (Fits 1 1/2" Dia. Tubing) $ 5.00 Qty: Add to Cart Tube Flange Mount: Material Type: Mild Steel Fits 1 1/2" Diameter Tubing Material Thickness: 3/16" Bolt Hole Diameter: 3/8" Outside Diameter: 3 1/2" 1 1/2" Diameter is oversize by .050 for fitment and welding.