Original laboratory trade vintage catalog for THE HAYS CORPORATION. Main office and factory was located at 900 East Eighth Street, Michigan City, IN. Manufacturers of Combustion Instruments. Pointer Gages for Draft, Pressure, Differential, Portable Combustion Test Sets, CO2 Recorder Model C and Combustion Test Meters. Unbound from a large 1931 engineering catalog, this unique old one page technical brochure would exhibit beautifully matted and framed. A fantastic addition to your retro industrial instrument collection. Slight damp stain on outer edge.