The parts of the element are made from electrical conduit and a water heater element. PVC is not rated for heat so my son felt that electrical stuff was better. The flap of rubber is to cover the bung hole to keep out bugs and such. The box part on the top points the same way as the curve of the water heater element so you can know where it is sort of when you can not see it.
Brandon chose the largest element that the tractor supply place had. I do not know if this is really needed because no matter what it is going to take a while to heat your oil. The elbow and everything fits through a 2 inch bung hole.
The complete unit can be moved from drum to drum. We only built one but did not put the heaters in the drums permanently because we knew we would have to have the heat to move oil from every step here in the winter time. And for us here in the middle of March it is still hovering around freezing most days. I want them to build a second unit when they get done with the truck so I can work two barrels in a day.