What is this RK05 style pack?

[Ashley Carder]

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?

Ashley