Unlike the photo on the product page, what arrived was actually a complete kit for replacing our Balboa 5.5 kW M7 heater. It included everything seen, plus two high-voltage wires with a connector attached to the studs on the heater housing, plus the connection for these two wires to the circuit board, plus two seals and silicone sealant for the slip housings.
I'm glad the voltage lines were already firmly attached to the studs, as this prevented me from having to tighten those nuts myself with the possibility of damaging the epoxy seals.
The brand seen in the product photo is Therm Products. This is the parent company of Balboa. What actually arrived for us was the Balboa version. We would have been fine with either one, as they both qualify as OEM.
The product came with instructions, and installed easily. FYI, the instructions say to put dielectric grease (not supplied) on the voltage line connections.
Our exact heater model is 58083. The unit has been installed for two weeks, and is working as expected.