D'Addario Helicore Cello String Set, 4/4 Scale, Heavy Tension 4/4 size cello with a playing length of 27 1/2 inches (700mm) Heavy 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