StringSpec
String finder

Browse all 789

Gamma

IO Soft 15L (1.40)

Polyester Gauge 15L 1.33 mm In production

Lab measurements for Gamma IO Soft 15L (1.40), 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

220lb/in

lower = softer, kinder on the arm

Tension loss

33%

lower = stays where you strung it

Energy return

88%

higher = livelier, more free power

Spin potential

6.3

higher = more spin off the string bed

Ball bite

0.418COF

higher = grabs the ball harder

Snapback

0.066COF

lower = strings slide and snap back

How it ranks against all 789 strings

Stiffness 220 lb/in · 87th pct

Stiffer than 87% of strings tested.

Tension loss 33 % · 54th pct

Sheds more tension than 54% of strings tested.

Energy return 88 % · 46th pct

Livelier than 46% of strings tested.

Spin potential 6.3 · 84th pct

More spin potential than 84% of strings tested.

Ball bite 0.418 COF · 36th pct

Grips the ball harder than 36% of strings tested.

Snapback 0.066 COF · 2nd pct

More string-on-string friction than 2% of strings tested — slides and snaps back freely.

Strings that play like this

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

Head Lynx Touch 16g (1.30) 97% match Head Lynx Tour 16 (1.30) 96% match Solinco Hyper-G 16 Round (1.30) 95% match Tecnifibre Black Code 15L (1.32) 94% match Head Hawk 16 (1.30) 94% match Gosen Polylon Premium 16 (1.32) 94% match

More from Gamma

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 IO Soft 15L (1.40) against 789 strings Find the right string for me