WW2 Military Hat Pin Eagle EPLURIBUS UNUM

This is a WWII era screw back hat pin. It is an officer's het pin, but I'm not sure what rank. It features the Eagle and E Pluribus Unum It has a screw back, and there are two sharp spikes that would have held it straight on the hat, but they have been altered to make it less likely to poke someone, I guess. It is curved to fit the front of the hat well. It is marked on the back: Gemsco and Acid Test. I believe it is good plated Measurements shown, but it is 2.5" x 2.75".