Fender strings have been around for a long time and have been the choice of a huge amount of players for decades.  These acoustic strings feature an outer 80/20 bronze wrap wire.  80/20 Bronze is a blend of copper and zinc and is synonymous in producing a lovely big, bright projecting tone that sings and can cut through the mix.   

Here's what Fender say about these strings:
Fender 80/20 Bronze Wound strings give your acoustic guitar a vibrant voice. With their full, clear sound and smooth, articulate feel, these copper-zinc strings deliver rich, lively tone that's ideal for brightening acoustic performance.