JB Industries DV-40 Electronic Vacuum Gauge is an advanced digital vacuum gauge that ensures proper vacuum on an AC system by providing accurate readings down to 10 microns. The JB Industries DV-40 requires no additional calibration out of the box, reads in multiple unit values including microns, PSIA, INHG, pascals, TORR, MTORR, and MBAR on a large LCD screen, and has a variety of user-programmable settings including an alarm for a user-defined vacuum point.