Infiltrator is a perk in Fallout 3, Fallout: New Vegas, and Fallout: The Roleplaying Game.
Fallout 3 and New Vegas
“The Infiltrator perk gives you a second attempt at a lock that you previously broke while trying to force it.”— Fallout 3 in-game description
With this perk, you get an additional try to pick a lock after failing a "force lock" attempt.
Fallout: The Roleplaying Game
When attempting a Lockpick skill test to unlock a door or container, the perk owner may re-roll 1d20.