Martin MSP7750 SP Lifespan - 92/8 Phosphor Bronze 12-str Baritone Acoustic Strings Treated with Martin's Cleartone proprietary technology for a longer lifespan than regular strings Made for 12-string baritone acoustic guitars 1st set: .012, .018, .026, .034, .047, .070 2nd set: .013, .018, .011, .016, .023, .034 92/8 bronze provides a bright and vibrant tone