Laser cut, the all-welded construction Retro-mate® adapters are available. The Retromate offers a fast, cost-effective method of replacing rooftop HVAC units. The old rooftop unit is removed, and then the curb is installed on top of the existing curb to adapt it to the new rooftop unit. Existing ductwork can be utilized. The company offers a superior weld with the tightest tolerances available today through advanced laser technology, claimed the manufacturer. The roof curb is factory prefabricated of heavy-gauge galvanized or Galvalume® steel. It includes 1 ½-inch, 3-pound insulation, transitions, baffles, and structural supports that mate the new rooftop unit to the existing curb and ductwork. The manufacturer has maintained a comprehensive library of discontinued rooftop literature and specifications which oftentimes permits the fabrication of mating Retro-mate curb without extensive field measurements, said the company.