Stalcraft Wiki: IP-4M

In-game description (EXBO)

The IP-4M closed-circuit breathing gas mask, which comes with a reinforced cloak, is popular among green stalkers. Although Reseacrh Institute 7 is a leading manufacturer of protective equipment against anomalies, many inhabitants of the Zone prefer artisanal products due to their affordability.

Quoted from the game's own text in EXBO's public game data. Not written by STALCRAFT Meta.