Our Mod Kits will be discontinued in August of 2020

Mod kits
more sound = less effort

Mod Kits available for nearly every make and model brass instrument

30 years of research in one package

Flexibility to play seamless wide intervals

Slotting increases accuracy

Stability in all registers at any dynamic

how does it work?

Jason Harrelson, founder of Harrelson Trumpets, discovered something revolutionary
while playing his friend's Bach Strad back in 1992.
Want to know the rest of the story?

Adding Efficiency with mass?

Have you heard that adding mass will darken the tone? Or that heavy bottom caps reduce flexibility?
Both of these myths have been proven to be untrue in numerous experiments and you can learn why here.

What to expect

SWE Mod Kits reduce energy loss in the sound wave, thus increasing efficiency.
This translates to playing with less effort, improved attacks, flexibility, slotting, endurance and dynamics.

Will it fit?

All Harrelson Mod Kits are guaranteed to fit your specific horn.
We offer a full money back guarantee and/or exchange on all Mod Kits that do not fit your instrument perfectly.
All Mod Kit sales are final unless otherwise specified.

how do i order?

call or email us

303.657.2747

which size?
  • Extra Light 1/4" - light attack, less projection
  • Light 3/8" - moderate attacks, more feedback to the player (.65 ounces)
  • Medium 1/2" - balanced, improved flexibility, solid attacks and slurs (1.23 ounces)
  • Heavy 3/4" - very efficient, crisp attacks at all dynamics, extreme flexibility, less feedback to player (1.83 ounces)
  • Heavier caps truly do not add much more efficiency, yet these are a popular option in 1" to 3" lengths

inlays & engraving

We offer every type of inlay and engraving for your Mod Kit

30 day guarantee

We offer a full money back guarantee and/or exchange on all Mod Kits that do not fit your instrument perfectly.
All Mod Kit sales are final unless otherwise specified.