It is a mandrel bent 3-1/2" pipe for 87-93 Mustangs that puts the ProM 77-92mm shorty mass air and air cleaner in the fenderwall for a cooler intake charge for added H.P. Additional benefit is better driveability with the bigger cams. Does not include Mass Air Meter or Air Cleaner. Works only with 77-83mm Pro-M Shorty.