The R3100-NIST is REED's higher-range digital manometer, covering gauge and differential pressure up to 100 psi with the same 11 switchable units (psi, bar, kPa, inH2O, and others). It offers 0.1 psi resolution, roughly +/-0.3% of full-scale accuracy, a backlit display, and onboard Max/Min memory, running on a 9V battery with auto shut-off after 20 minutes idle. Suited to heavier-duty HVAC and pneumatic/gas system troubleshooting as well as pressure-transmitter calibration, it includes a NIST-traceable calibration certificate.