Features: Professional Manometer: it can test the differential pressure of areas and pipes, wind velocity of pipeline. It has wide pressure range and +/-0.1% accuracy. Clear Display: 2.7-inch LCD screen with backlight display for easy reading. 12 Selections of Measuring Unit: hpa, kpa, mmHg, psi, mbar, bar, ozin2, inHg, Kgcm2, inH2O, ftH2o, cmH2O. Other Features: Max./Min. value measurement function, data record, data hold and zero function. User-friendly Prompt: low battery indication, Hi and Lo over range indicator. Low Power Consumption & Power Saving: powered by 3pcs AAA batteries(NOT included), and it will automatic power off after no operation for 15 minutes. Compact Size & Lightweight: easy to operate and carry, it also comes with a protective zipper pouch. Wide Applications: applied on chemical industry, electrical industry, nuclear industry to measure the difference of air pressure, etc Specifications: Model: AS511 / AS511B (Optional) AS511: Differential Pressure Measuring Range: -39.98~39.98KPa Maximum Permanent Load Pressure Range: -79.96~79.96KPa Pressure Resolution: 0.01KPa Accuracy: ±1%FS, maximum error: ±400Pa AS511B: Differential Pressure Measuring Range: -206.8~206.8KPa Maximum Permanent Load Pressure Range: -413.6~413.6KPa Pressure Resolution: 0.1KPa Accuracy: ±1%FS, maximum error: ±2.08KPa Measurement Selection Rate: 0.5 seconds Unit: hpa, kpa, mmHg, psi, mbar, bar, ozin2, inHg, Kgcm2, inH2O, ftH2o, cmH2O Temperature Measurement Range: -10~60 Humidity Measuring Range: 5~99%RH Temperature Accuracy: ±2 Humidity Accuracy: ±5%RH Storage Environment: -10~70 / -4~140 Power Supply: 3 * 1.5V AAA battery (NOT included) Material: ABS Item Size: 167 * 65 * 30mm / 6.57 * 2.56 * 1.18in Item Weight: 141g / 4.99oz Package Weight: 305g / 10.77oz Package Size: 24.8 * 9.3 * 5.3cm / 9.76 * 3.66 * 2.09in Package List: 1 * Manometer 1 * Package of Accessory 2 * Plastic Pipe 1 * Zipper Pouch 1 * Manual(English)