Sample 1:

Possibly prototype of removable plate bags that did not make it into the final Aircrew Endurance vest.  Made of lighter weight (500D cordura?) Coyote Brown material. Has hand-written labeling like other modern prototype/test items (source:  CMU-37 is for crew and CMU-38 is for (co)pilot (source:

Arms on Backside:

It is unclear what these attach to since the platebags were not found with any other components.

Plate Bag Openings:

Final Aircrew Endurance Vest:

121217-N-JQ696-001 NAVAL AIR STATION PATUXENT RIVER, Md. (Dec. 18, 2013) Marines demonstrate the redesigned aircrew endurance survival vest, with improved ballistic protection, superior load distribution and a new universal color for deployment in a wider variety of terrains. The vest attained initial operational capability Nov. 27, a key milestone for Naval Air Systems Command’s Aircrew Systems Program Office based at Naval Air Station Patuxent River, Md. (U.S. Navy photo by Kelly Schindler)

Image above from this article about the vest: