When the turret is lifted from a Tiger, it reveals a flat ring welded to the hull roof. The ring has a pattern of holes, depending on the Tiger's version.
This is the earliest version of the ring. It has 24 bolt holes plus a few openings for various turret mechanisms.
If you lift the turret from Rye Field's model to see the hull interior, the ring is revealed.
Rye Field's ring has two notches for locking the turret into place; of course there were no such notches on the real Tiger.
For their first Tiger kit, Rye Field modelled the original version of the ring. They placed the 24 bolt holes correctly, but they omitted some of the openings at forward left. They also made 4 new holes (marked here) that don't exist on real Tigers.
Although the Mid and Late Tigers have different rings, Rye Field copied this Early ring into their Mid and Late kits. Even the transparent roof of their "Wittman" kit (shown here) has the same layout. I have pointed out that the four imaginary holes are present on the transparent ring.