Vickers Tank Periscope MK.IV

The Gundlach Periscope, usually known under its British designation as Vickers Tank Periscope MK.IV, was a revolutionary invention by Polish engineer Rudolf Gundlach, manufactured for Polish 7TP tanks from the end of 1935 and patented in 1936 as the Peryskop obrotowy Gundlacha. It was the first device to allow the tank commander to have a 360-degree view from his turret with a single periscope.

Source: Wikipedia — Vickers Tank Periscope MK.IV (CC BY-SA 4.0)