Product Description Sunbeam phosphor bronze strings are hand wound on round cores which give a terrific result .Wonderful sustain .Remarkable sustain. The tone does not seem to decay as do Other phosphor bronze strings, which we think of as decaying in a curve. The Sunbeam phosphor seems to sustain in a straight line, until the sound "falls off". The Sunbeam phosphors are also musically bright and rich sounding. Additionally they are very flexible .More So than any Other string we have played. From the Manufacturer SUNBEAM™ Acoustic Guitar Strings utilize a phosphor bronze wrap wound on a round high-carbon steel core. The use of the round core increases flexibility and produces a long sustain that fades slowly and evenly without any sudden drop-offs. SUNBEAM™ phosphor bronze strings are musically bright and rich sounding.