Vintage Linen tester Magnifier 9X 1/2" - JAPAN - SMD components review

[Kiriakos GR]

Among the tools that I got from my father, he was cars electrician at 80s, this is and a weird looking loop magnifier.
This is made in Japan, but there is no brand or model labels.

After playing with Google search for hours, I did discover that I own an Linen Tester. 
In the past three decades I was using it so to read IC and transistor part codes, and a few times for Surface mount components inspection.

My vintage magnifier, this seems to have been made by I.L.K Japan (IKEDA Lens ).
It base has measuring lines that I could not identify,  and found the answer in the USA, it has a window of 1/2" X 1/2" inch, this be divided four times.
This is a very weird detail, how its possible a Japanese tool, this designed for inches, this to be found in Greece?
And in the hands of a cars electrician?

Either way I will pass a few links, for anyone interested to discover and another style of magnifier.   
Japan http://www.ikeda-lens.co.jp/en/products/7521.php
USA (similar item) https://www.magnifier.com/10x-metal-linen-tester-lt10.htm

The amazing detail about this tool, its designed for minimum distortion at the entire open window (cut-out)  13x13mm in metric.
Lens diameter 14mm
Magnification    9 times
Weight 15 grams