American Hammered Piston Rings, 1936

Life, November 1936

According to their website:

American Hammered began in 1912 - the Original OE Piston Ring supplier. Back in 1912, Albert Wenzel developed a machine to hammer the inside of piston rings to provide tension which resulted in better sealing and longer engine life. By 1918, he made 250,000 rings per month - the American Hammered Piston Ring.