Equipment Glossary

The area of the string bed, measured in square inches. A larger head (100+ sq in) gives a bigger sweet spot and more power margin on off-centre hits. A smaller head (95–98 sq in) offers greater precision and control, but demands a more consistent swing. Most tour players use 97–100 sq in.

Alcaraz uses 98 sq in — typical for high-swing-speed players who don't need extra power.

How heavy the racquet is once strung and ready to play. Heavier racquets (300g+) transfer more mass into the ball for depth and pace, and absorb vibration better. Lighter racquets (under 285g) are easier to manoeuvre and swing fast, but give up some stability on heavy balls.

Most ATP players use racquets in the 330–360g range — often much heavier than the retail frame due to lead tape customisation.

Where the racquet's centre of gravity sits. "Head-light" (below 320mm) means more weight in the handle — easier to swing quickly and manoeuvre at net. "Head-heavy" (above 330mm) means more mass up front — more power and depth from the baseline without needing a big swing.

Serve-and-volley players favour head-light frames; baseline power hitters sometimes prefer head-heavy.

A measure of how much effort it takes to swing the racquet — specifically, resistance to rotation about a point 10cm from the butt. Unlike total weight, swingweight captures both the mass and where that mass is distributed. Higher swingweight (330+) means more stability and plow-through power; lower (under 310) means faster swing speed.

Swingweight is the single best predictor of how a racquet plays — more reliable than head size or weight alone.

How much the frame flexes when it impacts the ball. Measured on the RA scale — higher RA means stiffer. A stiffer frame (RA 70+) returns more energy to the ball for power, but transmits more shock to the arm. A more flexible frame (RA below 63) absorbs shock better and gives more feel, at the cost of some power.

Players with arm injuries or tennis elbow often switch to frames with RA 60–65 to reduce impact stress.

The number of vertical (mains) and horizontal (crosses) strings in the head. An open pattern (16×19) leaves bigger gaps between strings — the ball pockets deeper at contact, generating more spin and feel. A dense pattern (18×20) gives more control, consistency, and string durability, but less natural spin.

Most ATP topspin players prefer 16×19 or 16×20 open patterns.

The cross-section thickness of the racquet's frame, measured at its widest point. A thicker beam (26mm+) is stiffer and provides more inherent power. A thinner beam (under 22mm) is more flexible and gives better feel and feedback — characteristic of traditional player's frames like the Wilson Pro Staff or Babolat Pure Strike.

The thickness of the string. Common gauges run from 1.15mm (very thin, maximum feel and spin) up to 1.35mm (very thick, maximum durability). Thinner strings bite into the ball more for spin and feel, but snap sooner. Thicker strings last longer. Most tour polyesters run 1.25–1.30mm.

Sinner uses HEAD Hawk Touch at 1.25mm — the thinner gauge for extra feel despite polyester's typical stiffness.

The dominant string type on the modern tour. Polyester strings are stiff, durable, and hold tension well. Their low friction and firm response allow heavy topspin to be generated reliably. The trade-off is arm stress — polyester transfers more impact shock than softer alternatives.

Over 85% of ATP tour players use a full polyester or poly-dominant hybrid setup.

Made from cattle intestine, natural gut is the most arm-friendly and highest-tension-maintaining string available. It gives excellent feel, power, and comfort. The downside: expensive, poor in wet conditions, and wears quickly. Often used as mains in a hybrid setup with polyester crosses.

Djokovic uses natural gut mains with Luxilon Alu Power Rough crosses — a classic hybrid prioritising feel and tension retention.

Constructed from hundreds of tiny fibres bundled together, multifilament strings mimic the feel of natural gut at a lower cost. They're arm-friendly, powerful, and comfortable — popular with recreational players or those with arm issues. Less durable than polyester.

A hybrid stringing uses two different strings in the same racquet — one for the vertical mains (which do most of the work contacting the ball) and another for the horizontal crosses. A common tour setup is natural gut mains with polyester crosses: gut provides feel and power, poly adds durability and spin texture.

When you see "natural gut mains / Luxilon Alu Power crosses" in a player's data, they're using a hybrid.

How well a string retains its strung tension over time. All strings lose tension after stringing — natural gut and multifilament hold tension better than polyester. Low tension maintenance means the playing characteristics change quickly; high maintenance means more consistent feel throughout the string's life.

A rating applied to strings (and frames) that reduce impact shock transmitted to the arm and elbow. Natural gut and multifilament strings score highest; stiff polyesters score lowest. Combined with a flexible frame, an arm-friendly string setup can significantly reduce the risk of tennis elbow and other overuse injuries.

String tension is measured in either kilograms (kg) or pounds (lbs). To convert: 1 kg ≈ 2.205 lbs. European players and coaches typically refer to kg; North American contexts use lbs. On this site, both are shown — click the toggle on player profile pages to switch units.

Alcaraz strings at 23–25 kg (50.7–55.1 lbs). Sinner at 28 kg (61.7 lbs). Higher tension = more control.

Higher tension (tighter strings) produces a smaller trampoline effect — the ball comes off the racquet with more control and precision, less power. Lower tension (looser strings) creates a bigger trampoline effect — more power, comfort, and spin potential, but less directional precision. Most tour players balance this at 23–29 kg for polyester strings.

On player profiles, tension data is labelled by confidence level. "Exact" means a confirmed single value (e.g. 28 kg). "Range" means the player uses different tensions depending on conditions (e.g. 23–25 kg). "Approximate" means the figure is reported but not officially confirmed. "Unknown" means no data is available.

Takes the ball early, hits with heavy topspin and power from the back of the court, and looks to dominate rallies. Tends to favour open-pattern racquets (16×19) for spin generation, medium-to-high tension, and stiff polyester strings for control at high swing speeds.

Carlos Alcaraz and Rafael Nadal are archetypal aggressive baseliners.

Relies on consistency, defence, and redirecting pace rather than generating outright winners. Often uses heavier, more stable frames and softer tensions to neutralise heavy shots. Excellent at retrieving and extending rallies until the opponent makes an error.

David Goffin and Alejandro Davidovich Fokina are classic counter-punchers.

Comfortable on all surfaces and in all areas of the court — can baseline, serve-and-volley, and transition effectively. Tends to use balanced equipment: medium head size, moderate weight, neither extremely stiff nor extremely flexible.

Attacks the net frequently behind the serve or return. Favours head-light, manoeuvrable racquets for quick volleys and reflex shots. Less common on the modern tour due to baseline-dominant playing conditions, but still seen on grass.

Stays at the baseline and constructs points through consistency and placement rather than aggression. Often uses high-tension setups for control and predictable trajectory. Distinct from aggressive baseliners in that the focus is on consistency over outright power.

A frame built to professional specifications that differs from the retail version sold to the public — different moulds, different materials, often different weight distribution. Players then customise further with lead tape, silicone, or grip adjustments. When a player's racquet shows "(customised pro stock)" it means the retail version on shop shelves is not what they're actually using.

Djokovic (HEAD PT113B) and Sinner (TGT 301.4) both use frames unavailable at retail.

When a pro player switches to a different racquet or string model. Tracked on this site's Gear Changes feed. Changes often coincide with new sponsorship contracts, injury-driven adjustments, or performance tuning for a specific season or surface.

The ATP (Association of Tennis Professionals) governs the men's tour; the WTA (Women's Tennis Association) governs the women's tour. Rankings on this site reflect current ATP and WTA world rankings, updated weekly.