Do you ever find that after playing, you have clear marks from the mouthpiece on your lips and around your mouth? Perhaps you're pressing the mouthpiece against your lips too hard. I think a certain amount of pressure is necessary when playing high notes. However, if you're pressing the mouthpiece too hard across all registers, you might be losing lip flexibility, making it difficult to do lip slurs or produce a rich sound. This "METHODICAL ACCESSORY DEVICE (Non-Presser)" is an item designed to address such issues. In other words, it's for learning how to play with minimal pressure. You use it by inserting it between the mouthpiece and the instrument. When playing, if excessive pressure is applied to the mouthpiece, air will leak, and the sound will not be produced. You can change the tension of the internal spring by turning the shank part that inserts into the instrument. Start by adjusting the spring force to be strong, and gradually weaken it. By doing so, the burden on your lips will be reduced, which will help you develop an efficient playing technique and flexible lip slur practice. *When attached, the length of the tubing will increase. The pitch will also be lower. ■Tenor/Bass Trombone