This clamp is a means of fixing either 30 or 50mm duct systems to 1 ½ and 2 inch ladder racks. It is attached to the rack by a plate and two screws, which clamp the rack between the plate and clamp body. Multiple holes provide vertical adjustment in 21mm increments. It is used in conjunction with 30 and 50mm duct mounting brackets (Part No’s. TC1279-148A & TC1279-147A).