The EPHUM24 means that you can set the humidity level of the environment you want to dry using a simple dial, & is designed for use with the Ecor Pro DH800/DH811 & DH1200/DH1211 dry fan & INOX models only. All Dry Fan units have a humidistat built in but if they are placed in a roof void, under a floor or hidden in a cupboard, then this humidistat will give a faster reaction time to humidity change. This unit is also low voltage so is safe for use in the bathroom area only 12V signal through a 2 core wire. Completing this unit is a robust manufacture for long-term reliability. Comes as a complete set with humidistat, 5m of cable & small plug for quick connecting to the Ecor Pro models. Please note tolerance factor on the humidistat can be up to +/- 5% to that of the value shown on the control dial.