GP-5 Markings
The GP-5 has two stamps on either side of the mask, location circled in red below:
Both sides have a size stamp, in this case size 0. Size 0 is the smallest with 4 being the largest. The "У" after the number designates that it's the upgraded version.
And on the other side is a stamp that tells you where the mask was made, and in what month:
The numbers on the top stamp after the "Ф" designates the production lot. The stamp underneath tells you where it was made and the month.
If your mask has a "Т" it was made in Tambov,
"М" for Moscow,
"С" for Saratov
And "Я" for Jakowlew.
1 Dot means it was made between January - March
2 Dots means it was made between April - June
3 Dots means it was made between July - September
4 Dots means it was made Between October - December
So in my example, It was made in Tambov between October and December, with the production lot being 815.
If your mask has a "Т" it was made in Tambov,
"М" for Moscow,
"С" for Saratov
And "Я" for Jakowlew.
1 Dot means it was made between January - March
2 Dots means it was made between April - June
3 Dots means it was made between July - September
4 Dots means it was made Between October - December
So in my example, It was made in Tambov between October and December, with the production lot being 815.