Tecnifibre 4S Tennis String Tecnifibre 4S is a spin-optimized co-polyester string designed for modern baseliners who need heavy topspin production, confident control on aggressive groundstrokes, and the firm, precise response that polyester construction delivers in a string built specifically around spin-friendly geometry. The "4S" name references the four-sided (square) cross-section that creates the textured, edge-rich contact surface players use to grip and snap over the ball at contact — generating more spin RPMs per unit of swing speed than round-profile polyester strings that present a smooth, even contact face. At moderate tensions, 4S provides the responsive, low-powered control that full polyester construction is known for, while the shaped profile enhances the spin production that makes heavy topspin a reliable, repeatable shot rather than a high-risk gamble on each swing. Four-Sided Square Profile for Spin Generation - The square cross-section creates four edges that contact the ball at impact, gripping the ball surface more aggressively than a round string and generating the spin-producing snap-back effect — when the ball compresses against a shaped polyester string, the edges bite into the ball covering and the string deflects and returns to position, adding spin RPMs that smooth-profile strings cannot match at the same swing speed and string angle. Co-Polyester Construction for Control and Durability - Built on Tecnifibre's co-polyester formulation rather than standard monofilament polyester, 4S offers a slightly enhanced texture and performance profile compared to basic poly strings — firmer than multifilament for the precise, low-powered response that aggressive baseliners need for confident cross-court and down-the-line targeting without the string bed sending balls long on full swings. Firm Response for Targeting Precision - The firm, inelastic response of polyester construction limits the power amplification of the string bed, giving players direct, predictable control over ball placement on aggressive groundstrokes — meaning the ball goes where the racket is aimed rather than being amplified by string trampoline effect, which is the fundamental reason polyester strings dominate professional and advanced amateur play on both tours. Suitable for Full Poly or Hybrid Setup - 4S performs well as a full-bed setup for high-swing-speed players who generate their own power and need maximum control, or as a cross string in a hybrid setup with a multifilament or natural gut main to combine the spin production of the shaped poly cross with the power, comfort, and feel of a premium main string — versatile for players who want to experiment with hybrid configurations. Tension Maintenance for Consistent Session Performance - Co-polyester construction loses tension more slowly than cheaper polyester alternatives over the first hours of string use, maintaining a more consistent tension level through the playing session — important for competitive players who need the string bed to perform consistently from the first game to the last rather than feeling noticeably livelier as tensions drop through a long match. Recommended for Intermediate to Advanced Polyester Players - The firm, low-powered response of 4S is appropriate for players with developed swing mechanics who generate their own pace — players who rely on string power to generate ball speed will find polyester strings underpowered, but players with modern, full-swing groundstroke technique get maximum benefit from the control and spin combination that 4S delivers. String Specs — Tecnifibre 4S Construction Co-polyester monofilament Profile 4-sided (square) Gauges available 16 (1.30mm), 17 (1.25mm) Recommended tension 45–60 lbs Playing style Baseliner / spin player Set length 12m (40 ft)
