This unique device can be used to test SCUBA regulators for inhalation/exhalation effort plus first stage intermediate pressure and lockup stability. All tests can be done without dismantling the regulator. To check intermediate staging pressure, merely attach the BC hose to the tester's inlet fitting, pressurize the regulator, and read the gauge. A push button vent allows rapid cycling of the first stage for repeated testing or depressurization after completion of testing. For measuring second stage breathing efforts, simply insert a special adapter into the mouthpiece and breathe on the unit. Inhalation/exhalation resistances in inches of water can be read directly from the 4.0", dual-scale (2.0"), Magnehelic gauge. Housed in a tackle-box like carrying case, the tester has a lift-out tray where parts and tools can be carried. This compact and portable device is ideal for field repairs, charter boat operations, classroom demonstrations, or small repair centers which do not require more elaborate equipment.