Amprobe TH-1 [3311871] Compact Probe Style Relative Humidity Meter. The Amprobe TH-1 Relative humidity temperature meter is a small portable meter you can take anywhere for quick comfort-level measurements.The TH1 has an easy to read, dual display for RH and temperature, with data hold to freeze measurement results on the screen. The Amprobe TH-1 also measures wet bulb and dew point, and stores min/max reasings for comparisons. The TH-1 is a precision capacitive RH sensor with twistable protective cap.