The 4S tennis string from Tecnifibre is designed to maximise the spin potential thanks to a squared-up shape, and the co-poly monofilament construction offers superior elasticity to generate more power without procuring arm fatigue. It’s a great choice for heavy-hitting players who prefer a weightier frame and tend to break strings frequently. The Thermocore outer layer offers more resistance and exceptional flexibility, and the string is designed and manufactured in France. Shipped as a 12.2m (40ft) set.