Trumpet mouthpiece booster. Cone-shaped, made of raw brass. Currently, this specification is out of stock domestically, and I recently ordered it from KGU in Ukraine. I've only tried it out for a short while, so it's in good condition, but since it's raw brass, there is some minor wear and tear. Please examine the photos and understand before purchasing. Loved by many trumpet players, including Arturo Sandoval. When attached, the sound noticeably tightens, becoming dark, mellow, and similar to a heavy model, making it ideal for lyrical playing like ballads. Arturo Sandoval seems to use it in this way as well. Also, as the manufacturer states, it should stabilize and make articulation easier. It also works very well with heavy instruments. If your mouthpiece is too light and seems to be overpowered by the instrument, attaching this will improve the balance and make it much easier to play. It can be attached to standard mouthpieces like Bach, but it may be difficult to attach to special-shaped mouthpieces or instruments. To attach it, first pass the smaller, screw-shaped ring through the mouthpiece and secure it, then screw in the booster body. It's relatively easy to attach, and when securely fastened, you'll get a pleasant, resonant vibration. You can find detailed instructions on how to attach it on KGU's YouTube channel and website.