We offer this only for the extreme cost conscience customer. The reason is simple: with the above assemblies, you get the element, sensors, coupling, and housing. When you add it up individual prices, it's a good deal. Plus they are much simpler to replace. But some want the barebones replacement, and this is it. You have to remove the heater assembly, remove the element and insert the new element. Caution must be taken when installing the new element. If you don't install the new element sitting in the middle, the element will hit the side of the heater housing when the pump is on and make a clacking sound.