These strings are a new innovation from Cleartone.
They a Copper Bronze (E String), Phosphor Bronze (A&D strings), and an 80/20 Bronze (G string).
Cleartone EQ's are the first Acoustic Guitar Strings that blend a variety of metals into a single set to highlight your guitar's frequency response. Designed to mimic a "perfect EQ setting", each wound string utilizes a different alloy to enhance that string's natural frequencies. They started with a 99% copper-bronze for the Low E to increase bass response. Phosphor bronze is used on the A&D strings used to accentuate the mid range while maintaining a robust, low and high end. They selected 80/20 for the G string because of its bright characteristics and ability to cut through the mix. Put together, Cleartone EQ's produce an exquisitely balanced tone that mimics a "perfect EQ setting" by combining all the best characteristics of Phosphor Bronze, 80/20, and Copper-bronze into a single set.