Strings are anti-rust plain steel and Phosphor Bronze coated with Nanoweb, their HD Light gauge, 013 017 025w 032w 042w 053w. Developed in conjunction with Taylor Guitar for use on their Grand Concert and Grand Auditorium guitars. Makers say: “The HD Light set is ideal for players who are looking for the light hand feel of a light gauge set but want more articulation and a bolder quality out of their guitars.”