The 850B sets include black nylon trebles and Golden Alloy basses. These strings will produce purer treble tones and higher overtones on the bass strings.- Warm tone- Tension: Medium- String Gauges: Black Nylon .028, .032, .040, Golden Alloy: .029, .034, .041- Made in the USA with American Wire- Packaged using MAP Technology (Modified Atmosphere Packaging) to prevent tarnishing and ensure freshness