Ernie Ball Folk Nylon acoustic guitar plain strings are made of a solid nylon clear filament. Nylon produces rich pure treble tones with percussive attack. Ernie Ball folk nylon wound strings are made of 80/20 bronze wrapped around a multifilament nylon core. The plain and wound strings both feature ball-ends for convenient string changing. Gauges .028 .032 .040p .030 .036 .042.