By comparing the air temperature, slab surface temperature and room humidity, it can be determined what the dew point is. This instrument makes it easy to determine the temperature at dew point by pushing the "td" button. For moisture to condense in this situation, the surface must be 57 degrees. A general rule is to allow 5 degrees of margin, here 57 + 5 = 62 degrees, in which dew point can be a danger.