This product is aimed to measure positive and negative different pressure value. Here are some units of measurements for choice: InH20, psi, bar, mbar, kPa, inHg, mmHg, ozin2, ftH2O, CMh20 kgcm2. The product is equipped with simple hose connection. It is suitable for the measurement of ventilation and air Clean rooms, or any troubleshootings gas pressure system. Easy operation and clear reading.