Vault 22 cave door keycard

 is a miscellaneous item in Fallout: New Vegas.

Characteristics
This key card is used to access the cave in vault 22. The cave is the only way to get to the 6 HEPA 20 Cartridge Filters you need to complete the Still in the Dark quest

Location
On the fourth floor/commons area there is a door with a sign that reads Quarters. This door is locked with an average difficulty lock, but can also be bypassed using the terminal in the overseers office.Past the Quarters door The Key Card is located in the first room on the left. Just inside the room door on the right is a shelf. The Key Card is sitting on a stack of papers on the shelf with the lamp(see picture).

Bugs
The card may not always appear and you may need to leave and come back later.