WWI era American Red Cross Motor Corps car badge

World War One era American Red Cross Motor Corps metal and enamel car badge. The badge itself is circular and has a broad green enamel border with the words 'Motor' at the top and 'Corps' at the bottom in contrasting white enamel. The centre of the badge is an enamelled red cross on a white background. There is a thin metal border around both sides of the green band and the edges of the red cross.
The reverse of the badge is plain metal which appears to be a copper alloy. The maker's details 'Geo. J. Mayer Co. IND'P'L'S' appear at the top. There is a metal bracket attached to the reverse with a hexagonal nut. It has a longitudinal slot at the upper end used to adjust the height of the car badge. At the lower end of the bracket is hexagonal bolt and washer with a square nut on the other side, used to attached the badge to the vehicle. There is some surface rust on the front of the bracket where it has rubbed.