D'Addario Helicore Viola Single D String, Extra Long Scale, Medium Tension Extra long-scale viola (body length 17 inches and larger) with a playing length of 15 3/4 inches (400mm) Medium tension Stranded steel core provides optimum playability and produces a clear, warm tone Versatile string that works well for a wide variety of playing styles and instruments All D'Addario strings are designed, engineered and manufactured in the USA to the most stringent quality controls in the industry