From manufacturer:
Think of everything you wish for from your strings. Brilliant, richly resonant and responsive tone. A sound that packs a punch and stands up in the mix while lasting up to 3X longer than a standard string. No need to consult a genie. Just pick up a pack of Blue Steel strings. Worldwide Best seller backed by 100% Guaranteed Satisfaction.
Crafted of 92% Copper and 8% Zinc, Blue Steel acoustic strings are cryogenically frozen with a blast of liquid nitrogen which gives them these special, if not magical qualities. By freezing our strings down to -320ºF, we tighten the molecules, minimizing microscopic gaps. This process removes transient frequencies that produce harsh highs and muddy lows, creating a more consistent string, with true tone and longer life.