Obligato Full Size Viola C Stark
Pirastro Obligato D, G and C have a composite core. The A has a Steel core. Many strings of this type are bright and focused, but Obligato has a warm gut-like tone. Obligato D, G and C are often used as a custom set with your choice of Steel Core A string such as Pirastro Evah Gold, or Larsen. However the strings work well as a complete set.