PIRASTRO KEMAN TELİ OBLIGATO SET. Pirastro Obligato has a composite core. They are one of the most popular of this new type of string construction. Long life, warm gut-like tone, and stability in climate changes are the features of this string. The Chrome A is a brighter, more powerful version of the aluminum A. Evah Pirazzi, also from Pirastro offers similar construction but has a more soloistic tone. For a small size string of this type, also consider Violino, from Pirastro.