Inside material :Hexagonal nickel alloy Outside material:Nickel alloy Packaging :Paper box Inner packing :Vacuum packaging The strings of ORPHEE-DE series has strong durability with the vigorous and deep timbre. The alloy surface is oxidation-proof for its multi-layers processing.For senior guitar players DE-3X inch 010 013 017 026 036 046 mm 0.25 0.33 0.43 0.66 0.91 1.17