1. trumpet mouthpiece decompression valve, corrective blowing, beginner practice, improve the tone. 2. Professional breath practice, adjustable pressure. 3. Silver plated, brass, trumpet mouthpiece pressure reducing valve, very good air density, adjustable spring to help adjust the exact direction of movement of the lip muscles and endurance. 4. Beginner practice, adjustable spring strength; the role of the pressure reducing valve is to control the pressure of the lips when you blow, requiring the practitioner must be the correct vibration to produce a natural playing effect, the to enhance the tone. 5. Precision and sensitivity, reduce the pressure of the mouthpiece, the pressure of the mouthpiece is strengthened to a certain extent, the spring is compressed, no hair sound, only in a relaxed state, you can blow a normal sound. Colour:Silver Material:Metal Size:8.1x2.8cm Package Contents: 1 * Professional Correction Assistant Tool Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.