String comparison
RPM Blast vs Firestorm
Babolat RPM Blast against Signum Pro Firestorm: ratings, specs and which one fits your junior.
The short answer
Both are polyester strings. RPM Blast leads on spin and control. Firestorm leads on power, durability and tension hold. They score the same for arm friendliness (2/5). Firestorm costs less per set.
Ratings
Power
Spin
Control
Comfort
Durability
Tension hold
Ratings are on a 1–10 scale. The higher score is in bold when they differ.
Pick RPM Blast if…
- You want more spin (10 vs 8 out of 10)
- You want more control (9 vs 8 out of 10)
- Best for: heavy topspin players
- Best for: advanced juniors with fast, full swings
- Best for: players who generate their own power
Pick Firestorm if…
- You want more power (7 vs 6 out of 10)
- You want more durability (8 vs 7 out of 10)
- You want more tension hold (7 vs 5 out of 10)
- Your player is younger (recommended from age 13 vs 14)
- You want to spend less (from $9 vs $20 a set)
- Best for: powerful baseliners
- Best for: players seeking tour-level performance
- Best for: spin and control seekers
Specs side by side
| Spec | RPM Blast | Firestorm |
|---|---|---|
| Type | Polyester | Polyester |
| Construction | Octagonal high-density co-polyester monofilament | Round co-polyester monofilament |
| Gauges | 16, 17, 18 | 16, 17, 18 |
| Stiffness | Medium high | Medium high |
| Set price | $20–21 | $9–12 |
| Reel price | $130–150 | $90–110 |
| Arm friendliness | 2/5 · Low | 2/5 · Low |
| Cost to maintain | 3/5 | 5/5 |
| Recommended from | Age 14 | Age 13 |
| Levels | Advanced, Elite | Intermediate, Advanced, Elite |
| Play styles | Baseliner, Big hitter | Baseliner, Big hitter, All court |
| Junior tension | 46-50 lbs for juniors. String lower to unlock spin potential. Loses tension quickly so some players string 2-3 lbs higher. | 48-52 lbs for juniors. String at normal poly tensions. |
RPM Blast in short
Babolat RPM Blast is one of the most iconic co-polyester strings ever made. When Rafael Nadal showed up at the 2010 Australian Open with this octagonally shaped co-poly, it changed the game. The octagonal structure with high-density co-polyester adds phenomenal rotation to the ball. The slick surface enables the strings to snap back with vicious force, resulting in extra RPMs. One of the most popular co-polys of all time, this firm and durable string is perfect for big hitters looking to load the ball with pace and spin.
Firestorm in short
Signum Pro Firestorm is the ATP tour string that helped propel Matteo Berrettini into the top 10. Available in distinctive Metallic Gold, Firestorm offers the classic German polyester combination of spin, control, and durability that tour players demand. The balanced performance profile makes it suitable for aggressive baseliners who want to swing freely while maintaining placement accuracy.
RPM Blast vs Firestorm: quick answers
Which has more spin, RPM Blast or Firestorm?
Babolat RPM Blast, with a spin rating of 10/10 against 8/10.
Which is more arm-friendly for a junior?
They score the same, 2/5. RPM Blast is recommended from age 14 and Firestorm from age 13.
Which lasts longer?
Signum Pro Firestorm rates 8/10 for durability against 7/10.
Which is cheaper?
RPM Blast costs about $20–21 a set and Firestorm about $9–12, at typical retail.
The short answer and the "pick if" lists are generated from our ratings and junior data only. Data verified 2025-01 (RPM Blast) and 2025-01 (Firestorm).