A circular side hatch was put in the last two Tiger(P) turrets. It was present in Tiger "003" and this kit provides it, although some other kits of "003" do not.
A photo proves that it was the same hatch used in Henschel Tigers. It was a disc, locked by a heavy metal bar on the inside.
This is the inside face of that hatch in Amusing Hobby's kit. The vertical mechanism is the locking bar and its guides.
But on the left and right side of their hatch, Amusing Hobby have made large, deep hollows that were not in the real hatch. These depressions (arrowed) in the kit are a mistake. You could improve the kit's accuracy by filling them.