Therm Products C2550-3661-TI2 Heater,Low-Flow,Laing Tri-Bend 2000,15"x2-1/4",3/4"b,5.5kWThis is a generic replacement heater designed to work with the IQ2000 control box by Watkins Manufacturing only. The current generic replacement heater for the IQ2020 control box is 46-555-1015. An easy method of determining which version you have is to look at the sensors and where they attach to the control system. If they plug into the outside of the control box, it is an IQ2000 system. If they plug directly into the circuit board, it is an IQ2020 system. Control and Limit sensors on the inlet and outlet with 52" cords Features a push button reset high limit switch set to trip at 130°F 48" power cord 316L Stainless Steel Housing Contains a titanium element 6-8 gpm minimum flow rate required