The Red Keycard is an advanced-level clearance door key. Doors are requiring the red keycard can be found at the more dangerous points of interest, such as Airfield, Military Tunnels, and Launch Site.
You can collect a red keycard from several points of interest—namely, Powerplant, Trainyard, Water Treatment, and Airfield.
Typically, you can find red keycards on a table in the rooms that require the Blue Keycard for entry.
To both retrieve and utilize a red keycard, you will also need an Electric Fuse.
The locked doors at points of interest do not have power, with each card reader is attached to a fuse box, usually a short distance away from the door itself.
Once you insert a fuse into the fusebox, you will have a limited amount of time to make it to the door and swipe the keycard.
Each red keycard has a limited amount of uses and will decrease its overall health each time you swipe it through a card reader.
Alternatively, you can sell any unwanted red keycards to the Bandit Camp Shopkeeper for 80 Scrap pieces if you have no interest in running the monuments.
For more information, check out our guide on red keycard locations: