Model #993030L

The Research and Development Department of Stomvi has conducted a study on the acoustic effect of the trumpet bottom caps and has incorporated a sound box inside the cap.
 
The effect is based on the intrinsic characteristics of the sound box in instruments such as the guitar or the piano, by creating harmonic oscillation through a vibration which improves the performance of the instrument.
 
They have the same characteristics as the Harmonic bottom caps but with a lower mass to avoid loading the total weight of the instrument.
 
This system is patented by Stomvi and is applicable to some trumpet brands (ask for information).