Made from uniquely refined co-polymer polyester with a soft molecular construction, the new Sonic Pro string offers superior control and touch for extra pop and spin. This exceptionally durable string offers excellent response and playability that meet the demands of todays best players. Sonic Pro is one of the softest polyester strings on the market. Gauge: 17 / 1.25mm Length: 40' / 12.2m Composition: Monofliament Copolymer Polyester Color: Black