accurate thermostat to check exact temperature in each room

[Sami Gren]

As winter approached, we all know about all the phone calls we get from tenants that the heat is not heating up the apartment enough, not to mention the big percentage of them that when we come to check it out the windows are open< ,

but I was looking for an accurate thermostat that I can carry around and get the accurate temperature to know what the temperature really is.

I want a very accurate one

  Thank you