@Salém I had to take a quick look into it and yeah- the way you were doing it completely overwrote the item class instead of inheriting it and then adding just the chemical part, so I rewrote it a bit.

Example:
[code]
class cfgPatches
{
class CBRN_Compat_Facewear_FM12
{
requiredAddons[]=
{
"fm12_respirator"
};
// Optional. If this is 1, if any of requiredAddons[] entry is missing in your game the entire config will be ignored and return no error (but in rpt) so useful to make a compat Mod (Since Arma 3 2.14)
skipWhenMissingDependencies = 1;
units[] = {};
weapons[]={};
};
};

class cfgGlasses
{
class None;
class avon_fm12: None
{
CBRN_protectionLevel = "1 + 2";
CBRN_overlayType="CBRN_gear\data\hud\overlay_style_round.paa";
};
};
[/code]

i'm not sure if it even works anymore lmao
but sure, feel free to do anything you want

You don't mind if I take this to integrate it into the new mod right?