I have an external 5.25" (no further markings) for the Amiga at my home. It has on on/off switch, a 40/80 selector and doesn't need the diskchange command. It also does not need a mountlist entry, in contrast to Commodore's 1020 diskdrive.
Exactly.
In 80 track mode, the drive functions just like any external disk drive. 40 track mode isn't really of any use. :-)