The Testo 521-3 (0560 5213) High Precision Differential Pressure Meter easily determines even the smallest differential pressures (up to +2.5 hPa). Its high accuracy and a resolution of 0.1 Pa make the instrument ideal for differential pressure measurements in clean rooms or for flue inspections. When used with a pitot tube, the internal pressure sensor measures flow speeds in the range of 0.01 to 3937 fpm.