The steel plug of the turret vision ports was augmented by a framework on the inside wall of the turret. Two side walls were bolted on, made up of several pieces as shown here.
The side walls combined with the plug to make an opening 160mm x 72mm, adequate for the vision block which was 150mm x 70mm externally. This model shows the vision block and the assembled framework. A rubber ring was placed between the vision block and the plug.
This is the Tiger at Bovington, with its original paint. A vision block is inserted in the plug. A faceplate for the frame was attached by a hinge at the bottom. There were two thumbwheels to tighten it up; they are missing from this example.
This example in the Saumur museum Tiger has been sprayed with green paint and is missing its vision block. The thumbwheels have been tightened up to lock the block in place and form a waterproof seal. Notice that a rubber head-pad was fixed to the top of the faceplate.
[2] Survey of vehicle 250122, Bovington, by David Byrden
[3] DW to Tiger 1