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 "Gundlach Peryskop obrotowy" . 
<triplet> 7TP <subj> 1935 <obj> service entry