The DV-22 reads vacuum in seven international units: microns, psia, inhg, mbars, pascals, torr, and mtorr. Effective micron range of 9,000 to 20. Low battery indicator alerts to replacing 9 volt battery (not included). Saves last vacuum read out after shut down. The unit is leak proof with an O-ring coupler to ensure proper register of vacuum. Powers off after 10 minutes of no use to preserve battery life. Nist traceable.  Ambient temperature 32 degrees f (0 degrees c) to 120 degrees f (48.9 degrees c). The T2-4 flare tee can be used to attach hoses to the gauge. Sold separately. 12 month warranty. Made in the usa. Please use p90009 as replacement o-ring.