Ranco # J10-6503-200. Similar to a thermostat except it responds to relative humidity rather than temperature. Consists of a humidity sensing element, adjustable setpoint cam and an electrical switch. The sensing element changes length in response to the exposed relative humidity to move the switch mechanisms at the appropriate switch points. Set adjustment screw to a certain limit; when that limit is reached a S.P.S.T. switch opens or closes. Outer dimensions, 86 x 26 x 40mm, excluding adjustment shaft and switch terminals.
