At the highest level of the stringmaker's art, Thomastik Versum cello strings were designed with no compromises, for the world's greatest cellists. Powerful, rich, and seamless, for the most demanding repertoire. The C and G are crafted with a spiral steel core, and wrapped in Tungsten and chrome, for massive projection, yet retaining warmth. The A and D have solid steel core with multi-alloy winding, and are designed for perfect physical and tonal balance with the C and G strings. 4/4 size.