HEPA 20 cartridge filter

The HEPA 20 air cartridge filters are miscellaneous items in Fallout: New Vegas.

Characteristics
They can be found in Vault 22 in a locker on the oxygen recycling level. It can only be accessed by the cave in vault 22 because the door leading to it is blocked by debris. They are used for repairing the air filtration system in Brotherhood of Steel's hidden bunker in Hidden Valley for the Still in the Dark quest.

Location
To locate the HEPA filters go to the fifth floor and go up the stairs and there will be a room that leads you to the third floor where the HEPA filter are.Then you will need to go threw a tunnel and it will lead to a room where the HEPA filters are for the brotherhood of steel. Head right in the room and you will see lockers lined up against the wall the HEPA filters are located in the locker to your far right.