The SG100D-05 and SG100D-08 are too small and their power requirements are too low to justify building an AC power supply into them like the larger SGx00 switches have, so they are wired to accept DC power and use an external power adapter (included) for connection to an AC environment.
There are really no optional components to these devices, so the BOM would be as follows:
5-port SG100D swich: SG100D-05
8-port SG100D swich: SG100D-08