The loader's hatch on the Tiger could be locked open, in the vertical position, by this plunger under the turret roof.
The plunger engaged with a hole in an arm that was welded to the hatch. This photo, and this diagram extracted from the manual, show that the arm is deliberately bent.
There is a reinforcement at the end of the arm. The diagram makes it clear that it's just a semi-circular piece of metal.
Tiger "131" has its original plunger, but its hatch arm was lost. The restorers created a replacement arm that does not exactly resemble the original.
The new arm is not bent like the original. As a result, it does not line up with the plunger. The restorers solved this problem by putting a long cylinder at the end.
The result is an eye-catching and incorrect feature on top of Tiger "131".