12-16-24W-32-42-53 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 increase in mid-range that seems the make the notes cut-through a little more.
Great strings, period. Good solid fundamental tone but with enough harmonics to keep it pretty, stay in tune forever (on my Guilds anyway) and love you long, long time. No finer string for Guild acoustics IMHO.