Pass Card

Pass Cards are items that are randomly encountered in Fallout 3.

Gameplay
The cards work in a similar fashion as a Metro Ticket but are not removed from the player character's inventory when interacting with a Metro Protectron and only work in their respective metro lines (the Red Pass Card for the Red Line and the Blue Pass Card for the Blue Line). In addition, they can be sold to any merchant.

Locations
Pass Cards are located in random places throughout the Capital Wasteland. They are dropped by Feral Ghouls, Centaurs, and may also be found on Trogs if  is installed.

A Feral Ghoul has 1.5% chance of dropping a Pass Card of either color. A Centaur has a chance of 0.6% and Trogs have a chance of about 0.4%.