This comes with a bulkhead - mount plastic temperature sensor. You drill a hole in your sink/tub/tray or whatever, then this controller kicks on the heating element when the temperature drops below the setpoint. Apparently these things cost $180 in 1981. I also have a heating element to go with it. You need a separate thermometer to set it with. I never used it for photography but I tested it by plugging a desk lamp into it and holding the sensor up to the light bulb and it kicked the lamp on and off so it seems to be working.
The heating element will triple the shipping cost so I am listing it separately.
Temp controller $20, heating element $15 or 5 if bought with the controller.
The heating element will triple the shipping cost so I am listing it separately.
Temp controller $20, heating element $15 or 5 if bought with the controller.