D'Addario Pro-Arte 4/4 Size Cello Strings are designed for serious musicians looking for the sound and feel of gut strings and the consistency of a synthetic core. Pro-Arte strings have clear, soft, rich tone. The A string is alum/perlon. The D and G strings are silver/perlon. The C string is tungsten-silver/perlon. G is available with tungsten winding in 4/4 size. Available 4/4-1/8 size. Heavy and light gauge available in 4/4 size.