Lang Tools (TU-32-21) Fuel System Restriction Test Gauge is for use on Compuchek test ports on the fuel systems of Cummins, International and Detroit Diesel engines, as well as other diesel engines that have been outfitted with the Compuchek test ports. The TU-32-21 contains a hose assembly with a female Compuchek fitting on one end and a 3-1/2", 30 inHg vacuum gauge on the other.