The Jo-Ral B5 Bass Trombone Wa-Wah Mute creates the most exciting tonal quality resulting in near-perfect intonation. They are made of spun aluminum and have been tested to perform evenly in all registers. With its unique acoustical design this mute sets the standard for wah-wah type mutes. Its distinctive shape conforms to the contours of the bass trombone bell to provide a powerful muted sound when needed.