CHICAGO EYESHIELD COMPANY
Chicago EyeShield Company (CESCO) made mostly industrial safety glasses. They also made industrial full and half face gas masks, some of which are described here.
The most common CESCO full face respirator is the CESCO Fume Mask, which was produced some time prior to World War 2. Patent number markings on the facepiece of the mask refer solely to the 1934 patent for the CESCO HealthGuard respirator, a supplied air mask designed by Malcom Robert.
The standard Fume Mask loadout came in a small metal box, with three sealed filters, each rated for different chemicals.