D'Addario J59 Pro-Arte 1/2 Size Cello Strings are designed for serious musicians looking for the sound and feel of gut strings and the consistency of a synthetic core. J59 cello strings deliver clear, soft, rich tone. The A string is alum/perlon. D and G strings are silver/perlon. The C string is tungsten-silver/perlon. And the G is available with tungsten winding in 4/4 size. Available 4/4-1/8 size. Both heavy and light gaugestrings are available in 4/4 size.