Check the listing for details. D'Addario Zyex Series Violin A String 4/4 Size Medium Aluminum. Color: 4/4 Size Medium Aluminum, Condition: New. Listed at 17.30 USD. Zyex synthetic core violin A strings produce an extremely warm, rich sound. Made from a new generation of synthetic material, Zyex strings are incredibly stable under drastic climatic conditions. Within a matter of hours, Zyex settles in on the instrument with a sound that is warmer than most other synthetic core strings. These strings are an excellent choice for use on bright sounding instruments.Scaled to fit up through 4/4 size violin, the 1/16 to 3/4 size strings are available in medium tension, while the 4/4 strings are available in light, medium and heavy tension. Zyex violin strings are packaged in uniquely-designed sealed pouches that provide unparalleled protection from the elements that cause corrosion.