heljestrand nr506

Anyone any info on this nr 506 model please ?
It's a tad over 6/8 , extra hollow ground .
Did a search but can not find anything about a nr 506Attachment 343469Attachment 343470 model...
Any clues anyone ?
Thanks

I have a No 130 and No 140, 6/8 and 7/8 respectively. I have heard that the razors stamped with the ‘No X’ are for foreign markets, and South America was mentioned. However, I bought the No 130 and bpth No 140 from Japan.

Hope this helps