Features:  LCD Backlight Screen, Unit Switchable -- High resolution digital LCD display with green backlight, easy to read no matter in the day or at night, clear at a glance. We provide 2 models for your option, whose measurement units are of different ranges and resolutions.  Dual Channel Pressure Gauge -- Quickly measure the pre-blue detection pressure value (relative to the current atmospheric pressure). Dual channel can simultaneously detect the pressure difference between two detection ports.  Temperature Measurement & Other Functions -- This digital differential pressure gauge can also be used for temperature measurement, and it supports ℃/ ℉ switchable. Data hold/ data storage (100 groups)/ data search function, maximum/ minimum data mode.  Dual Power Supply Method -- Powered by 9V battery (not included) or external USB cable. Low power MCU designed. Automatically shut down after 15 minutes idle time to save power. 6.8V low battery indicator for convenient use.  Scope of Application -- Widely used in natural gas pipelines, air-conditioning refrigeration and ventilation systems, mechanical hydraulics, plastic molding, ceramic products, biopharmaceutical molding, mining area pressure detection, petrochemical refining, gas, liquid, and production industrial equipment pressure detection.    Note:  1. Color and size may be slightly different due to manual measurement and different light conditions. Thanks for understanding.  2. Please read the user manual carefully before use.    Specifications:  Model & Color: 168B Red/ 169B Yellow (Optional)  Material: ABS  Unit of Measurement: kPa, Psi, kg/cm², ozin², bar, mbar, inHg, mmHg, inH₂O, ftH₂O, cmH₂O, Pa (Pa is for 168A only)  Accuracy: ±0.3% FSO  Repeatability: ±0.2% (MAX±0.5% FSO)  Measurement Rate: 0.5s  Data Storage: 100 Groups  Low Battery Indicator: 6.8V  Positive Pressure Range Display: Err0  Over Negative Pressure Range Display: Err1  Working Temperature: 0~50℃ (32~122℉)  Power Supply: 9V Battery (not included) or External USB Cable  Item Size: 164 * 71 * 35mm / 6.46 * 2.80 * 1.38in  Item Weight (without battery): 151g / 5.33oz  Package Size: 18 * 10 * 4cm / 7.09 * 3.94 * 1.57in  Package Weight: 267g / 9.40oz    Package List:  1 * Digital Manometer  1 * Air Nozzle  2 * Tube  1 * USB Cable  1 * User Manual (English)  1 * Carry Bag