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