Used Booster Ring for Trumpet Mouthpiece One-owner item (me). By attaching a booster to the shank of a trumpet mouthpiece, the weight of the mouthpiece itself increases, removing unwanted noise from the lips and transmitting more regular vibrations to the instrument. Please refer to the photos for the condition when attached to a mouthpiece. (※The mouthpiece in the photos is not included.) If anyone is interested, please let me know. Thank you. m(_ _)m