Vintage Superior Spring & Manufacturing Co. Car Parts Advertising Letter Opener.
Basing it on the way it's made with the advertising trapped in acrylic or lucite and the stamping of the metal, I would assume that it was made in the 1960s or 1970s. Has wear and scratches.
Measures 7” in length, 1 1/2” in width, and 1/8 in depth.
PP18