Gearbox has announced on Twitter that new "Dragons Keep" heads are now available via SHIFT codes for Borderlands 2. SHIFT codes are usable only by the developer's SHIFT Premiere Club.
"Look for these customizations to appear in Dice Chests in-game (more on that here) or click on each image above for a SHiFT code to unlock the head for that character immediately -- new images and codes will be posted daily through Sunday, August 18!!" Gearbox.
Players can sign up to the SHIFT Premiere Club directly in-game. To get the codes for the above heads, go.