Abstract: A tool is disclosed, for measuring the important thermal characteristics of a unit of electronic equipment, which obtains air flow and temperature readings at both air inlet and air outlet openings of the unit without disturbing cable or wiring connections or otherwise interrupting device operation. The tool pressure sensing element is rotatable between detented positions to permit the tool to be used at both air inlet and air outlet openings. The tool air duct portion may be formed of separate duct portions to enable a single duct portion including the sensing instrumentation to be used with multiple duct portions that conform to electronic device air inlet and outlet openings to impart added flexibility to the tool.