that is not a controller but a double relay, you can do the same with 2 single relays and can get 50 amp ones for $8 each brand new and brand name (even cheaper if you don't go for Bosch or similar, so i can't see how this would be cheaper than that other than having the integrated connectors). Problem is that you can't control the ON temperature, where the actual efficiency lies - it's the probe that gives that threshold where you run the fan when you shouldn't or just right so it doesn't turn on when the vehicle is moving, otherwise you fight the thermostat by closing and opening it unneccessarily.
