The Wilson Champions Choice Duo is a hybrid of the Natural Gut & the Luxilon ALU Power Rough tennis strings that provides excellent comfort & power as well as an amazing feel & enhanced durability. The Luxilon ALU Power Rough string has a gauge of 16L (1.25mm) & is 6.7m (21ft) long, whereas the Natural Gut string is 16 (1.30mm) in diameter & has a length of 6.1m (20ft). This quality hybrid string with a multifilament core is supplied as a 12.8m (42ft) long set that is enough to re-string one racket.