Original, US Army Officer's NUMBER FOUR, Private Contractor, Silver, Pinback, Regimental Number. 1/2"
Silver numbers were usually used in the center of officer's embroidered insignia worn on kepis, Burnside pattern, Hardee and slouch hats.
These particular numbers are some of the last remaining stock rescued from Bannerman's Island before the fire.
Manufacturer and date of manufacture is unknown.