The advanced power armor Mk II , also called black devil power armor or simply Enclave power armor, is a high-end model of power armor used exclusively by the Enclave's Department of the Army and developed after the Great War and the destruction of the Enclave Oil Rig in 2241. It is composed entirely of lightweight composites rather than the usual combination of metal and composite plates found on the previous designation of advanced power armor, the MK I. Its design is substantially different from another, earlier model of the MK II.