From the manufacturer:

The core material of all four string lines, Evah Pirazzi Gold, Evah Pirazzi, Obligato and Violino consists of a new synthetic material that we have co-developed with our supplier and which we obtain exclusively.

We are convinced that this new core material is superior to other synthetic materials and steel, because:

• it offers an unmatched wide range of sounds,
• absolutely insensitive to variations in temperature and humidity, and
• it offers musicians an unknown dynamic range.

In combination with our newest production techniques we are now able to offer a new family of strings, which offer:

• a complex tone, rich with overtones;
• bring out finest nuances in pp and great depth in ff;
• great playability;
• outstanding response and
• outstanding tuning stability
• which can be used in any environment no matter the degree of humidity or changes of temperature.