The Tecnifibre 4S is a spin-focused co-polyester string designed for aggressive players who want maximum bite, control, and durability. Originally known as Black Code 4S, this string features a square profile with sharp edges, making it one of the most spin-friendly polys in Tecnifibre’s lineup.
Built with Thermocore technology, it offers a slightly improved feel compared to traditional stiff polys, but remains a firm, control-oriented string aimed at high-level players.
Tecnifibre 4S Score
| Power | 5 |
| Spin | 9 |
| Comfort | 6 |
| Control | 9 |
| Durability | 9 |
A spin and control machine designed for big hitters.
Specs of Tecnifibre 4S
- Gauge: 17 / 1.25 mm
- Composition: Co-polyester monofilament with Thermocore technology
- Color: Black
The square cross-section and sharp edges maximize ball grip, while Thermocore processing helps reduce harsh vibrations.
Tecnifibre 4S Performance
Tecnifibre 4S is built for players who swing fast and want a low-powered, high-control string with massive spin potential.
Comfort & Feel
Comfort is moderate for a polyester. It has a firm and crisp feel, though Thermocore technology softens it slightly compared to older stiff polys.
The feel is more connected than plush, giving players clear feedback on contact.
Power & Control
Power is low. This string does not provide much free depth, allowing players to swing aggressively without fear of overhitting.
Control is outstanding. The firm construction and low power create a very predictable and precise response, ideal for advanced players.
Spin Potential
Spin is the standout feature. The square shape and sharp edges grip the ball extremely well, producing heavy topspin and sharp angles.
This makes it perfect for modern baseline play and high net clearance shots.
Durability & Tension Maintenance
Durability is excellent. The stiff co-poly construction holds up very well under heavy hitting.
Tension maintenance is also strong for a polyester, maintaining playability longer than many competing spin strings.
Pros
- Massive spin potential
- Excellent control and precision
- Very durable
- Strong tension maintenance
Cons
- Low power
- Firm feel may be harsh for some players
- Not ideal for beginners or sensitive arms
Who Should Use Tecnifibre 4S?
Tecnifibre 4S is best suited for:
- Intermediate to advanced players
- Aggressive baseliners
- Players with fast swing speeds
- Players who rely on heavy topspin
It is not recommended for beginners or players looking for comfort and easy power.
Final Verdict
Overall, Tecnifibre 4S is a high-performance spin and control polyester that excels in aggressive, modern tennis. Its sharp edges and firm response allow players to hit with confidence and generate heavy spin.
While it lacks comfort and power, it delivers exactly what competitive players need: precision, durability, and maximum spin potential.