Series 850 PSP - Classical guitar strings with polished surface, specially designed for high-grade recordings (studio). The The PSP-Technology (Precision Smooth Polished) helps to reduce finger noise during the change of positions, to the greatest possible extent. The bass strings are wound with a special wire and are polished (i.e. silver-plated, smoothed and polished). The treble strings are made of precision round nylon monofilament.