Spring Load
It allows the molecular chains to contract repeatedly, with minimal tension loss and greater stability of properties over time.
Arm Friendly®
String Project Sirius
Precise, stable, consistent: top-level performance.
String Project Sirius is a competition monofilament tennis string, developed with next-generation materials and additives and designed to deliver high-level performance. Its main strength is control (9.5/10): stable on impact and consistent over time, with 9/10 tension maintenance and 8/10 Arm Friendly® comfort.
8/10
Comfort
9.5/10
Spin
9/10
Power
Technical Specifications and On-Court Ratings
Control, Tension Maintenance and Comfort
String Project Sirius is a competition string with high performance across the board. Its main strength is control (9.5/10), with a stable response that sends the ball where you aim it. Tension maintenance (9/10) keeps this precision over time, and Arm Friendly® comfort (8/10) makes it playable even in long sessions. Spin (9.5/10) and power (9/10) complete a high-level profile.
Power9/10
Comfort8/10
Control9.5/10
Resilience8/10
Spin9.5/10
Tension9/10
Ratings measured in the laboratory by Pro-t-one (Eng. G. Medri), as are the technical specifications.
Characteristics and Laboratory Tests
Laboratory tests confirm Sirius's character: 9.5/10 control and 9/10 tension maintenance, with a stable response on impact. The dynamic stiffness of 225 g/mm keeps responsiveness and comfort in balance.
Technical Data Sheet
- Cross-section
- Round
- Available gauges
- 1,25 mm (16) · 1,30 mm (16)
- Dynamic stiffness
- 225 g/mm
- String Stiffness Emulator
- 220 lb/in
- Static stiffness
- 1.05 kg/mm
- Tension range
- 17 / 23 Kg
Laboratory test report · Pro-t-one (Eng. G. Medri)
Optimised Technology and Performance
String Project Sirius is developed with next-generation materials and additives, which give it more control and more stability without giving up Arm Friendly® comfort. The result is a competition string with high performance that stays consistent over time.
The manufacturing processes
Pre-Stretch
The pre-stretch of the core minimises tension loss and allows stringing at lower tensions.
Double Heating
The heat treatments remove internal stresses and any irregularities in the string, making it more uniform, flexible and elastic.
Liquid Wax
The string is finished with a layer of wax, which reduces wear, significantly extends its lifespan and makes stringing easier.
Low Friction
Reducing friction offers three advantages: less string movement, greater spin potential thanks to better snap-back, and a longer lifespan.
Top Performance, on Court
On court, Sirius stands out for its control (9.5/10): the response is stable and the ball goes where you aim it, even on the heaviest shots. Spin (9.5/10) and power (9/10) back up every shot, but it is precision that makes the difference. Arm Friendly® comfort makes it playable for a long time.
Precise and Stable
Sirius offers top-of-the-range control (9.5/10). Its stable response lets you direct every shot with precision; spin (9.5/10) adds effective rotation.
- Control 9.5/10
- Stable response on impact
- Precise directionality
- Spin 9.5/10
Consistent over Time
With 9/10 tension maintenance, Sirius keeps its performance over time. Arm Friendly® comfort (8/10) and natural power (9/10) complete the profile.
- Tension maintenance 9/10
- Consistent performance over time
- Arm Friendly® comfort 8/10
- Natural 9/10 power
What the Experts Say
Independent reviews published by testers and specialist outlets.
Who It's For
Competitors seeking control
Those who want to place the ball with precision and look for a stable response, even on the heaviest shots, with high performance in everything else.
Demanding amateurs
Those seeking high-level performance and more control, with the comfort of an Arm Friendly® string.
Those who want consistent performance
Those who need the string to keep its characteristics over time. With 9/10 tension maintenance, Sirius guarantees reliability session after session.
Ready to Reach the Top Level?
Choose the format that best suits your needs. Free shipping from €50.
200 m Reel
~17 stringings
-
~€6.41 per stringing
- Free shipping
- 1 Dampener
- 2x Dry Overgrip pack
Gauge:
Pack of 6 Sets
6 stringings
-
~€8.98 per stringing
- Free shipping
- 1 Dampener
- 2x Dry Overgrip pack
Gauge:
Pack of 3 Sets
3 stringings
-
~€9.97 per stringing
- Free shipping
- 1 Dampener
- 2x Dry Overgrip pack
Gauge:
Single Set
1 stringing
-
- Free shipping
- 1 Dampener
- 2x Dry Overgrip pack
Gauge:
Frequently Asked Questions (FAQ) about String Project Sirius
What is String Project Sirius?
String Project Sirius is a competition monofilament tennis string, developed with next-generation materials and additives. It offers control (9.5/10), spin (9.5/10), power (9/10) and Arm Friendly® comfort (8/10), with tension maintenance (9/10). It is the String Project string designed for control, with high performance across the board.
At what tension should String Project Sirius be strung?
The recommended tension range is between 17 and 23 kg. The wider range compared to the other strings in the range lets you customise the setup to your playing style: lower tensions for power and comfort, higher for maximum control.
Which gauges is String Project Sirius available in?
Sirius is available in two gauges: 1.25 mm (16L) for maximum spin and sensitivity, and 1.30 mm (16) for greater control and durability.
Is String Project Sirius suitable for players with arm problems?
Yes, Sirius is Arm Friendly®, with 8/10 comfort. Despite its high performance, its construction with next-generation materials and additives ensures good vibration absorption.
What is the difference between String Project Sirius and String Project Magic?
Sirius is oriented towards control (9.5/10) and tension maintenance (9/10). Magic is the soft string, oriented towards comfort (9/10), with the spin of a monofilament. Those who want precision choose Sirius; those who want softness choose Magic.
How long does String Project Sirius last?
Sirius has 9/10 tension maintenance, among the best in the range. It keeps its playing characteristics consistent for longer than most polyesters, guaranteeing reliability session after session.