4-Bolt Rectangular Connections

We started selling the 4-Bolt system for the assembly of rectangular ducts back in 1968. Certainly one of our most successful innovations.
Available in three sizes (20, 30 and 40 mm), and in galvanized steel, stainless steel and aluminum.
Two-Part Corners

For rectangular ducts with rolled-on flanges, such as the ones manufactured by FIRMAC duct-lines