Obligato is the best synthetic core string in the Pirastro family and is among the best in the world. The strings are produced with the highest quality winding and perlon core. Obligato strings deliver the same superior warmth and brilliance as the best gut strings while providing resistnace to temperature and humidity fluctuation unfounded in gut strings. Tonal quality is completely unsurpassed by any other perlon strings. The goldplated E string further complements this SET of superior strings by providing a very bright and responsive high register treble. This SET comes with an aluminum wound D string to provide a faster response to the middle register. Made in Germany. Available in 4/4 size only.