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:
 * Collecting resources from a production room
 * Rushing a production room
 * Sending a dweller or Mister Handy to explore the wasteland
 * Selling weapons or outfits
 * Leveling up a dweller
 * Completing objectives
 * Receiving them in lunchboxes, in units of 100 or 500
 * Finding and selecting the Mysterious Stranger