The Zeiss supplement is from an earlier date and actually made for the cupolas in the Westwall.
These persicopes had the specification 1 x 70 degrees and offered only a view dead ahead. In the main section “related” we show the armoured parts that were needed to fix this P.W.B.F.
Type Armour thickness Pz.B.W.F.1 40 cm Pz.B.W.F.1a 30 cm Pz.B.W.F.2 20 cm Pz.B.W.F.3 12 cm 
A specimen of the P.B.W.F.3, complete with eye-cup.
A box full of them.
This is a Zeiss number “2”.
