MA535S Authentic Acoustic Phosphor Bronze Custom-Light Guitar Strings are engineered with the performer in mind and they will always stand up to rigorous practice and performance schedules. Martin starts with the highest tensile-strength core wire, then tin-plate it on all six strings for added corrosion resistance; because what you don’t see matters. When coupled with Martin's highest-quality wrap wire you get consistent true tone that you can count on song after song. Martin Authentic Acoustic SP 2/8 Phosphor Bronze strings offer excellent tuning stability, corrosion resistance and great playability. MA535 Authentic 92/8 Phosphor Bronze Custom-Light guitar strings gauge: 11-15-23-32-42-52.