11-15-24W-10-30-14-42-22-52-28 43 inches 80/20 Bronze wound strings are often called old-school, vintage and/or bright bronze??and were the most popular (only) alloy used to make acoustic strings until the introduction of phosphor in the early Seventies. 80/20 bronze wire is made from 80 percent copper and 20 percent zinc. 80/20 bronze provides balanced highs and lows with a slight increased in mid-range that seems the make the notes cut-through a little more. It took several years of trial and error to develop a proprietary string coating the resists tarnish and corrosion without compromising tonal quality.
After a long search for a more traditional set of 12 string guitar strings, I found Mangan. On an equal footing with my former go-to set for 12 string! Will get back regarding string life and sound.
Choices are basically nil for "long-lasting" 12-string sets heavier than .010-.047 inch. I tune my 1989 Seagull S12 guitar down to C#. Typical 010-.047 inch sets are too floppy, and anything heavier than .011-.052 inch is harder to fret on a 12-string acoustic guitar. My fingers are so acidic that untreated strings start tarnishing after a few hours. This coated .011-.052 inch set lasted me over four months before showing any degradation!