Mike Fitzpatrick can be reached by e-mail to discuss badges.

Obverse Design Badge is based around a center circle. Above the circle is a perched eagle with spread wings. The eagle's head is ducked down and facing to its right (our left). The center circle has an inner circle with a large three-dimensional five pointed star. There is a raised edge and then an outer smooth circle with lettering. It has the legend "MASTER-AT-ARMS" above the inner circle and "N.A.S. COCO SOLO" below. There is a leafy border below the circle which drops to a point. On this leafy border is a small rectangle with the badge number of "9".
Reverse Design Vertical pin back. See image below.
Metal Appears to be made out of nickel silver per Mike Fitzpatrick (brass was in short supply during World War II). Size and Shape About 45mm wide by 69mm high (about 1 3/4 inches by 2 11/16 inches).
Dates Issued Probably World War II (1941-1945).
Issurer Coco Solo naval base. Coco Solo was a submarine base on the Atlantic side of Panama near Colon for many years. N.A.S. stands for Naval Air Station, and Mike Fitzpatrick speculates that PBY Catalina flying boats may have been stationed at Coco Solo. If so, they would have been there to protect the Canal and ships in the vicinity of the Canal from the Axis powers during World War II.
Numbers Issued Pieces known include #9.
Rarity Very Rare. Manufacturer Unknown. Source Sale on ebay by Mike Fitzpatrick.
Varieties None known.

Master-At-Arms vest badge. I would appreciate e-mail from anyone who can add anything to the history of these badges.

Reverse Side of Badge
Reverse side of a BG-40.1
Scale: 4 pixels equals one millimeter