from Pirastro:

• The A- and D-strings have a core made from a single filament of high-tensile steel and are wound with chrome steel. The G- and C-strings have a rope core wound with tungsten.
• The A- and D-strings are most brilliant.
• The G- and C-strings provide a big and powerful sound and have a short decay.
• very quick response
• exceptional tuning stability and immediate playability
• Suitable also for electric or electrically-amplified cellos