1-Superheat differential measurements: T1-T2, Air-T1, T1-Dewpoint. 2-Dual Type K external temperature probe inputs (T1, T2), Simultaneous display of %RH, Temperature and Dew point or Wet Bulb or External Probe Temperatures. 3-Built-in RS-232 interface, it uses optional Windows® 95/98/2000/ME/NT/XP compatible software. 4-Retrieve Max/Min readings with data and time plus Average function. 5-Real time clock. 6-Triple display with backlighting. 7-Unique sensor cap design twists to closed position for protection during storage. 8-Switchable °F/°C temperature units with 0.1° resolution. 9-Data Hold freezes current reading on display. 10-Auto power off to save battery life. 11-RH350 complete with two Type K bead wire temperature probes and 4 AAA batteries. 12-Optional RH355 kit includes RH350, 33% and 75%. 13-calibration bottles, PC software with cable and case. Made In USA.