D'Addario Helicore Cello Single D String, 4/4 Scale, Medium Tension 4/4 size cello with a playing length of 27 1/2 inches (700mm) Medium tension Stranded steel core provides optimum playability and produces a clear, warm tone Quick bow response and optimal playability All D'Addario strings are designed, engineered and manufactured in the USA to the most stringent quality controls in the industry