When browsing through tons of hat pages, its hard to tell which hat is a gas mask and which isn't.
The only way to tell is literally by walking through someone else's gas and I find this kind of frustrating during times where I'd find a hat to quick-equip from gassers, since some hats can look like gas masks but don't protect from gas at all.

So yeah, I thought having a small smoke icon above every gas mask or at least having 3 categorical sections like All, Gas-Protected, Normal, would protect this issue.