Bottle cap (Fallout Shelter)

Bottle caps are the currency in Fallout Shelter.

Uses
The bottle caps are required to expand your vault by building or making upgrades in any room.

Earning caps
You can earn caps by:
 * Rushing a room.
 * Collecting production from a room.
 * Completing objectives.
 * Exploring the wasteland.
 * Selling weapons / outfits.
 * Leveling up dwellers.
 * Receiving them in lunchboxes, in units of 100 or 500.