[Functional use]This product can measure differential pressure, positive pressure, and negative pressure, with the following optional measurement units: inH20, psi, bar, mbar, kPa, inHg, mmHg, ozin2, ftH20, cmh20, kgcm2. [Easy to use ]Equipped with a simple hose connection device. Suitable for measurement, on-site calibration, and troubleshooting of any gas pressure system in ventilation and air conditioning systems. [Widely applicable]Easy to operate and with clear readings, it is an indispensable measurement tool for HVAC technicians, operation and maintenance engineers, and scientific researchers. [Reading clearly] This instrument has the following functions: Pressure display value, data retention function, recording mode, maximum minimum value, average value, low battery prompt, difference display, unit display, and time display. [Note] Please measure within the range and do not exceed the maximum pressure specified in the "Technical Parameters", otherwise the instrument may be damaged. BT-189A Digital differential pressure gauge accuracy:±0.3% Linearity/hysteresis:± 0.1% of full scale Limit maximum pressure:6Psi Repeatability:±0.25% Automatic shutdown:About 25 minutes Pressure connection:/8inch (3.18 mm) quick connector Operating temperature:0~40℃ Storage temperature range:-10~60℃ Over-range prompt:ERR1 or ERR2 weight:134g Size:160 x 62 x 31mm Power supply: 2 x 1.5V AAA batteries (Not included batteries) Color: As Shown Material: ABS Package Contents: 1 set * handheld digital pressure gauges Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.