The testo 623 is a temperature and humidity measuring instrument which shows current and past temperature and humidity values in a large clear display. This makes an analysis of the current and past ambient conditions possible, directly on site and without time-consuming analysis on a PC. The Histogram shows current and past temperature or humidity values for the past 90 days. Histogram shows measurement values of last 90 days All important values at a glance Large, easily legible display Analysis of past temperature and humidity measurement values directly on site