DR Strings Rare - Phosphor Bronze AcousticHex Core Bluegrass 12/56 Gauge: Bluegrass (12, 16, 24, 34, 45, 56) Phosphor Bronze Acoustic Guitar Strings wound on Hexagonal Cores Low tension...the sound is loud and warm Hand-carved arch-tops, dreadnaughts and good steel string acoustic guitars made of rosewood, maple, and mahogany seem to benefit from a distinct improvement in tone, depth, and sustain with Rare phosphor strings Long lasting