Lang Compuchek Adapter is meant to be used with the Lang Tools 74438 gauge assembly, or the 74424 gauge assembly with the 74425 hose assembly The Lang Compuchek Adapter tool is a Compuchek quick coupler socket with a male quick coupler plug. Lang Compuchek Adapter is used to measure fuel pressure, check for air bubbles, and bleed air from the fuel system on the family of engines from Navistar/International VT365, DT466, DT570 and HT570.