Strings are cryogenically treated phosphor bronze wound on a plain steel hex core. Medium gauge, 013 017 026w 036w 046w 056w. Sealed in corrosion-free "NitroPack" packaging. Maker says: "With feedback from players young and old, we have developed a series of strings gauged for the current needs of the musician, and then cryogenically treated them to ensure that if you're playing into the night, these sets will continue to inspire and help you share your unique voice." Replaces the LJ40M set.