DR Strings Zebra - Acoustic-Electric Round Core 12-54 Gauge: Medium Designed for acoustic-electric guitars with piezo pick-ups under the bridge...or magnetic pick-ups in the sound hole Full size arch top jazz guitars also respond to "Zebras" with "Richer tones" according to players ANY amplified acoustic comes ALIVE when you put on the Zebra strings Every other coil is nickel-plated steel, every other coil RARE phosphor bronze