Project KEYSTONE

The KEYSTONE development program was a project undertaken by the Office of Naval Intelligence's Materials Group and Misriah Armory, with the intent of producing MJOLNIR Powered Assault Armor.

Development history
KEYSTONE was one of several armor projects undertaken by the Office of Naval Intelligence, designed to test the ever-evolving standard for the third generation of powered armor systems. The design was compatible with the GEN2 platforms, though was selected by Dr. Halsey as the basis for the later Mark VII.

Halo 4
The KEYSTONE helmet will be made available for use in Halo 4 as an armor permutation as part of the game's inclusion in Halo: The Master Chief Collection. The helmet is available as part of Season 7: Elite, as an Exchange-exclusive item. The helmet is free to unlock for all players, and costs to purchase. It was never available in Halo 4 for Xbox 360.

List of appearances

 * Halo 4