H46 SPACE HUMIDISTAT SPST contact action  provides dehumidifying  control. 
Used in Air conditioning humidity control. 

TRADELINE. DEHUMIDIFIER CONTROL WALL MTD. W/CASE AND COVER KNOB.
NYLON ELEMENT MAKES CIRCUIT ON RH INCREASE. 20-80%
Two wires SPST 6 Amp 120V

   Optional    Wired Humidifier - Dehumidifier