Versum Cello AThomastik Versum cello strings are among the warmest produced by Thomastik, and their sweetness is not without clarity and distinction. As the first choice of many notable professionals, Versum strings are capable of producing subtle and complex tone colors to match the cellist's advanced musicality. The Versum A and D strings have a carbon steel core and multialloy windings. Vibrating string length is 70mm 27. 6"