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Signum Pro

Poly Speed Spin 1.28

Polyester 1.28 mm In production

Lab measurements for Signum Pro Poly Speed Spin 1.28, 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

246lb/in

lower = softer, kinder on the arm

Tension loss

41%

lower = stays where you strung it

Energy return

85%

higher = livelier, more free power

Spin potential

4.3

higher = more spin off the string bed

Ball bite

0.480COF

higher = grabs the ball harder

Snapback

0.112COF

lower = strings slide and snap back

How it ranks against all 789 strings

Stiffness 246 lb/in · 99th pct

Stiffer than 99% of strings tested — punishingly firm — control at the cost of comfort.

Tension loss 41 % · 68th pct

Sheds more tension than 68% of strings tested.

Energy return 85 % · 19th pct

Livelier than 19% of strings tested.

Spin potential 4.3 · 37th pct

More spin potential than 37% of strings tested.

Ball bite 0.480 COF · 70th pct

Grips the ball harder than 70% of strings tested.

Snapback 0.112 COF · 78th pct

More string-on-string friction than 78% of strings tested.

Strings that play like this

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

Gamma Zo Ice 16 95% match Leopard Plus Control 16 94% match Babolat RPM Blast 16 93% match Pacific X Force 17 93% match Signum Pro Hyperion 16 93% match Prince Poly EXP 17 92% 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 Poly Speed Spin 1.28 against 789 strings Find the right string for me