Ernie Ball have long been renowned as the world’s most popular guitar string manufacturer. However they do tend to write rather opaque product descriptions! I have included their description of these strings below, but here is a brief synopsis from me. There are two main materials used for winding acoustic guitar strings- 80/20 bronze and phosphor bronze. Phosphor Bronze has a brighter, clearer sound but tends to rust a little faster, and 80/20 bronze is more mellow but maintains the same tone a little longer. You can find the 80/20 version of these strings here. Ernie Ball have also coated these strings with a proprietary nano-coating which makes them repel grease and liquid and consequently last up to three times longer than regular Earthwoods, hence their higher price (trust me- they’re worth it!).
Here’s what Ernie Ball say:
Ernie Ball Everlast Coated acoustic guitar strings use groundbreaking nanotechnology that repels unwanted moisture and oils that negatively impact your tone. Our proprietary treatment is applied to both the inner hex core and outer wrap wire to provide ultimate protection without compromising tone or feel. Made from 92% copper, 7.7% tin, 0.3% phosphorus wire wrapped around brass plated hex shaped steel core wire, Phosphor Bronze strings produce warm rich bass tones with clear bright trebles.