DR Strings Zebra - Acoustic-Electric Round Core 13-56 ZEBRA strings. It is the very first string where you can see the difference. .013 .017 .026w .034 .045 .056 - set / Acoustic (Electric) GuitarStrings for Electric-Acoustic guitarsMedium-Heavy Gauge2 Different windings at one coreNickel Plated Steel and Phoshpor BronzeRoundwoundRound CoreMade in USASpecially designed for Acoustic guitarsand Archtopswith piezo pickups under the bridgeor magnetic pickups in the soundhole. Also for full size archtop guitars which respond to ZEBRAS with richer tones according to players. Any amplified acoustic comes alive when you put on the