This is a "Mission Systems" control panel used on military helicopters and manufactured by Sikorsky Aircraft. A "MSN SYS" panel provides remote control of the operation of the cryptographic system. It mounts in the main panel with standard "Dzus" captive fasteners. The equipment depicted here was made in 1992.

(Can anyone expand on this explanation?)

Front View Rear and Bottom View

(Photos via E-bay)