If you want to use a mid-span bracket on 4" slotted duct that is adjustable to allow for an off-set from the frame, you would use part 027-2000-4060 + 027-1000-4117. The 027-2000-4060 would be installed onto the 027-1000-4117. The 027-1000-4117 is a 4” adjustable bracket for mounting vertical slotted ducting.