About this detail of the Tiger
The Tiger was originally designed with two pistol ports on the rear of its turret. Although these had integral armour covers, they would leak water if the tank were submerged. Therefore the ports were designed to be watertight when needed.
Sealing a port was done by inserting a special plug, seen in this wartime photo. The port had slots cut into it and the plug had a tab that, when rotated into the slots, pushed its rubber base tightly into the hole in the port.
Although every large item of the Tiger's internal equipment was generally given its own box or hanger, I have not found a place dedicated to storing these two plugs. However, information about the first few dozen Tigers is sparse.
In the 56th turret a new system of equipment storage was introduced. Most items on the turret walls were moved around, and the designers took this opportunity to give the pistol port plug a holder. It was placed on the turret roof above the one remaining pistol port. This is one such holder, in the Bovington museum Tiger.
In the summer of 1943 the Tiger's turret got a major redesign. The new turret, which we call a "Mid" turret, had a completely different type of pistol port. The plug was no longer necessary and it did not exist in "Mid" or "Late" turrets.