I found this image, one had it as avatar on SHAMO:
Ring a bell?

Ring a bell?
Haha it's the weak part on those things. When I was in the military one guy had the filter neck cracked when he was in the tear gas room.frissy said:I once busted my filter in the military and "neck" of the thing broke off and got stuck in the mask. It was a real bitch to remove.
"WHERE IS YOUR FILTER!" "Well sir, a funny thing happened"