Interesting is that none of the packs I sell have the mask adaptors with them. It's not a standard item.
Type M is for the masks most used by the U.S.
However, one caveat:
It makes no difference if you are using a gas mask with your Camelbak while using a standard reservoir (in a lethal-gas or biological agent environment). CB makes reservoirs specifically for use in gas environments that are impermeable to outside substances (including the drink-tubes). While standard reservoirs can likely stand up to tear agents, they should not be used in lethal gas or bio-hazard environments.
Those reservoirs, however, DO come with the mask adaptors.
