A couple months ago I acquired a new, still in the
plastic wrap, still in the box, never opened disk
pack that at first glance appeared to be an RK05.
I finally decided to look further at it to see if
it was a 12 sector or 16 sector RK05 pack, since
it had no identifying label or markings.

Upon further inspection, I found that it did not
have the usual rim on the hub, where normally
you would be able to count the thin notches to
determine whether it was a 16 sector or 12 sector
RK05. Instead, it has a short, rounded, unnotched
rim where normally it would have the tall thin rim
with notches. Otherwise it looks just like an RK05.
The case is interchangeable. I actually took it
apart so I could use the case on another RK05 pack
that had a decent platter but a bad outer case.

What is this thing? RK03?