Gas mask's maker's stamp question

[The woodpecker]

Good evening mates.I have for some time a ww2 British markv gas mask.I am just curious.Have you ever seen such a stamp on a MkV gas mask?['cause the circle isn't the same as the majority i have seen]Many Thanks

[NCA]

All my respirators are in storage at the moment so i cant compare but i have seen that mark before.
I'll bet its short for 'Dunlop Rubber Company.
The '3'?..possibly a mold number..

[The woodpecker]

I am much obliged mate.This was very useful

[The woodpecker]

I think that the number 3 it's the month of constraction

[37Webbing]

I think that the number 3 it's the month of constraction

No I don't think so, I think it is a size.

It is common for gas masks to be made in 3 - 4 different sizes. 1 being the smallest and 3 (sometimes 4) being the largest.

That is at least what I think it is.

[The woodpecker]

The size is stamp at the other side of the mask: Normal...