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 faster installation. Gauges .028, .032, .040p, .030 .036 .042