Set of four tumblers that are guaranteed! Crescendo barware is machine blown in Parma Italy and made in Luigi Bormioli’s proprietary SON.hyx material. SON.hyx produced glassware is an exciting fusion of elegance and technology. In addition to having ideal bowl shapes, fine rims, and beautifully drawn stems, glassware made in SON.hyx is extremely brilliant in color, has a beautiful sound, maintains its clarity after thousands of industrial dishwashing cycles, and possesses an extremely high level of durability and strength. The stems are also reinforced with titanium. Luigi Bormioli has developed an unprecedented guarantee program for these glasses! The 25 Year Guarantee covers chipping on the rim or foot as well as any discoloration or cloudiness resulting from washing.