The GSP / GSP-M type mask was intended for use in fire fighting (with SCBA like AP-3 or AP-3M) and chemical industry (with filtering appliances or hose apparatuses like AZ-2M, AT-4M, AS-3M etc.). It's main advantage is double layer visor with a layer of glue in between glass panes. Such construction prevents air leakage even when the visor glass is damaged. The wiper, despite looking like an useful feature is here because of a poor design - the mask has no oro-nasal cup nor a ventilation system - the wiper is the only way of improving visibility.

Through out majority of the mask production period it was manufactured in one, universal size. Some instruction manuals mention the 3 different sizes: 1 - small, 2 - medium, 3 - big.

In earlier versions the production date was put as a stamp underneath the leather seal around the mask. Later the date was embossed on the inside of the mask as a "clock" with a year in the center and a quarter on the perimiter. Different versions with different exhale valve covers existed - the earliest being GSP. The newest version used a plastic pop-on cover.

Maska #1
Manufacture date:	1989
Size:	1

In this version a plastic pop-on exhale cover was used. Instead of using a spring-pressed plate as an exhale valve, a more standard, rubber "mushroom" type valve is used in case of both the exhale, and an inhale valve, thus unifying the construction. Such valves can be easily replaced using the MP-4 repair kit or spare MC-1 exhale valve.

Maska #2
Manufacture date:	1979
Size:	1

Maska #3
Manufacture date:	1976
Size:	2

I've got this specimen with an instruction manual mentioning the 3 sizes. Earlier and later manuals state the masks was produced in one, universal size.

Maska #4 (GSP)
Manufacture date:	1964
Size:	---

An interesting, very early example. Produced by Fabryka Sprzętu Ratunkowego (FSR), which stamp is barely visible. Considering the photos from books I assume it is a GSP - an older version of this model. The difference being an exhalve valve cover.