Original vintage ad for MINNESOTA MINING MANUFACTURING COMPANY.  3M Soundtalk Tartan Magnetic Tape for 4-track stereos. Uniformity of oxide thickness is held to microscopic tolerances to keep dynamic range identical throughout each reel, each track, from reel to reel.
Main office was located in St. Paul, MN.
This unique old one page 1961 high fidelity stereo equipment trade magazine advertisement would display beautifully matted and framed.  It would make a nice accompaniment to your vintage stereo.