Feature 1PRESSURE RELIEF: This valve can help the performer reduce mouth pressure during trombone playing, improve comfort and control performance. 2BRASS MATERIAL: This pressure relief valve is made of excellent brass, ensuring good durability and reliability, corrosion resistance and wear resistance. 3SKILL CORRECTION: Can help trombone players correct the wrong mouth posture and techniques, improve sound quality and playing techniques. 4GOOD COMFORT: Adopting ergonomic design, this pressure reducing valve can effectively reduce discomfort in the mouth and face during performance. 5EASY OPERATION: This pressure relief valve is suitable for various models of trombones, easy to install and adjust, suitable for performers of all levels.Item Type: Trombone Pressure Relief ValveMaterial: Brass .wang-edit-text{ font-family:'Arial' !important; } .wang-edit-text table { border-top: 1px solid #000; border-left: 1px solid #000; } .wang-edit-text table td, .wang-edit-text table th { border-bottom: 1px solid #000; border-right: 1px solid #000; padding: 3px 5px; } .wang-edit-text table th { text-align: center; }Package List1 x PressureReliefValve1 x Storage Box