The Protimeter Humidity Box can be used in conjunction with either the Hygromaster or the MMS and MMS2 hygrometer instruments in order to take surface relative humidity readings (%rh) on concrete floors and wall slabs. Using the humidity box is simple and straightforward: the foam block humidity box is placed on the floor and then the Hygrostick is inserted into the hole on the side. When connected via the extension port on the hygrometer, the Hygrostick then provides the relative humidity reading of the cavity within the box.