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Signum Pro

Firestorm 1.25

Polyester 1.25 mm In production

Lab measurements for Signum Pro Firestorm 1.25, ranked against all 789 strings in the database. Every figure below is a testing-machine result at a fixed reference tension, not a playtest opinion.

Measured values

Stiffness

198lb/in

lower = softer, kinder on the arm

Tension loss

46%

lower = stays where you strung it

Energy return

87%

higher = livelier, more free power

Spin potential

4.8

higher = more spin off the string bed

Ball bite

0.413COF

higher = grabs the ball harder

Snapback

0.086COF

lower = strings slide and snap back

How it ranks against all 789 strings

Stiffness 198 lb/in · 66th pct

Stiffer than 66% of strings tested.

Tension loss 46 % · 81st pct

Sheds more tension than 81% of strings tested.

Energy return 87 % · 37th pct

Livelier than 37% of strings tested.

Spin potential 4.8 · 51st pct

More spin potential than 51% of strings tested.

Ball bite 0.413 COF · 32nd pct

Grips the ball harder than 32% of strings tested.

Snapback 0.086 COF · 36th pct

More string-on-string friction than 36% of strings tested.

Strings that play like this

Closest matches across stiffness, tension loss, energy return and spin potential.

Kirschbaum Pro Line II 17L (1.20) 96% match Gamma Zo Twist 16 95% match Luxilon Big Banger TiMO 17L (1.17) 93% match Head Ultra Tour 16 93% match Tourna Big Hitter Silver Rough 16 93% match Tecnifibre Black Code 18 93% match

More from Signum Pro

What these numbers mean

Stiffness · lb/in

How much the string bed resists deflection. Higher plays firmer and more controlled; lower plays softer and easier on the arm.

Tension loss · %

Share of the reference tension the string sheds under a fixed test protocol. Lower means the bed stays where you strung it for longer.

Energy return · %

Share of impact energy handed back to the ball. Higher plays livelier and more powerful.

Spin potential

Ball friction divided by string-on-string friction. Higher means better bite with a cleaner snapback, so more spin.

Ball bite · COF

String-on-ball friction. Higher grabs the ball harder through the brush.

Snapback · COF

String-on-string friction. Lower lets the mains slide and snap back into place after impact.

Compare Firestorm 1.25 against 789 strings Find the right string for me