The Pz.Rbl.Z.F. series was used for grenade launchers. The M.19 is a very advanced 5 cm mortar that was designed for use in fixed fortifications. It was for instance used in the bunkertype 633 with armoured turrets type 424P01 or 428P01. The 10.5cm howitzer in turret (Turmhaubitze L/14 M100) in bunkertype 664 also used this persicope. These cupolas were of type 73P9 (102 t) or 81P9 (45 t).
The series has following types:
A very fine and complete set.
And there is even a second one.
(Member "Kreta" on forum.axishistory.com.)
This is a specimen of the "3".
It was mounted on the weapon, but could rotate 360 degrees independently.
On the lower left you see the turning knob for rotating the mirror in the head. The angle was presented on the dial around the eyepiece.