Wilson champions choice duo tennis string the wilson champions choice duo tennis stringis a hybrid of the natural gut and the luxilon alu power rough tennis strings that provides excellent comfort and power as well as an amazing feel and improved durability the luxilon alu power rough string has a gauge of 16l 125mm and is 67m 21ft long whereas the natural gut string is 16 130mm in diameter and has a length of 61m 20ft this quality hybrid string with a multifilament core is suppl