The Protimeter HygroMaster L thermo-hygrometer measures relative humidity, air temperature, dew point, and specific humidity (GPP, g/Kg). At the time of purchase, choose between the the short QuikStick for fast-responding full-range measurement or the HygroStick sensor for harsh and high-moisture applications such concrete floors. Both are also available as accessories to purchase in addition or later as replacements. The surface temperature sensor is also available as an accessory.