About this detail of the Tiger
The armour thickness of the Tiger 1 mantlet is usually quoted as 100mm or greater. In fact, part of the earliest Tigers' mantlet was only 70mm thick.
Tigers initially had a binocular sight and so there were two openings in the left side of the mantlet. These openings were narrow on the inside but tapered outwards to give a good field of view. This model is a subsection of the mantlet, showing how the holes appeared on the outside.
The diagram above is a plan view, cutting through the mantlet to show both holes. On the inside the holes are 13mm wide, but the outside is 35mm in diameter.
The mantlet is nominally 80mm thick in this area, but in the immediate vicinity of these holes the inside face is hollowed down to 70mm. This is the inside of the same section.
The diagram above shows the size of the hollowed area. Later, a bulge was added to the mantlet in order to protect this vulnerable area.
This diagram shows the same area, from above, with the protective bulge. The outer face of the bulge is angled. The thickness of the armour is at least 100mm. Notice that another step has been added to the tapered holes.
As you can see here, the holes now appear larger on the outside.
Later still, it was decided to close up the left-hand hole with a welded plug, whose design you can see on .