Used Heavy Bottom Cap for XO / JUPITER One-owner item (me). Simply replacing the normal bottom cap with a heavy bottom cap reduces unwanted vibrations, changing the tone and playing feel. In the example photo, it's attached to the 3rd valve, but attaching it to the 1st or 2nd valve will also make a big difference. On the instrument I use, when attached to the 2nd valve, the sound became more vibrant, and high notes became easier to play. Attaching it to all three valves makes the instrument itself heavier, increasing resistance considerably, but it gave the impression that the noise in the sound was almost completely eliminated. It should be possible to install it on instruments with the same screw diameter and pitch, but I cannot guarantee it. If anyone is interested, please let me know. Thank you very much. m(_ _)m