HVAC / R conditioning refrigeration industry used to measure pressure difference.facilities.Measuring negative pressure setting to indoor pests will not pollute the in the outside world.Measure positive pressure.Peripheral Pneumatic Control Equipment.Maximum / Minimum / Average Read Write Function. backlit LCD display.Reset, offset and data offset.Set the low battery display and auto off function.Data Retention and Error Code Functions.Over / Under Indicator Range.The user can re-calibrate the meter at any time.Pressure Range: + 2psiAccuracy: + 0.3% FSO (at 25 Celsius)Repeatability: + 0.2% (Max + 0.5% FSO)Linearity / Hysteresis: + 0.29% FSOResponse Time: 0.5 SecondsAbove Display Range Indicator: HiUnder Display Range Indicator: LoOperating Conditions: 0-50 Celsius (32-122 Fahrenheit)Storage Conditions: -10-60 Celsius (14-140 Fahrenheit) Supply: 9V BatteryColor: blackMaterial: ABSSize: 150*55*40mmPackage Contents:1 * Digital Manometer(without battery)2 * Plastic Hose1 * Metal Connector1 * Carry PouchOnly the above package content, other products are not included.Note: Light 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.