Thomastik-Infeld's Spirocore cello string set features a flexible spiral core built to project a warm tone without losing volume or power. 3/4 and 1/2 sets are chromium wound. ?4/4 sets provide two types of D and A strings and 3 types of G and C strings. ?The lower two strings come in chromium, silver or tungsten. Paired with Larsen's A & D strings, the tungsten Spirocore G & C are one of the most popular strings among cellists.