The adjustable Jo-Ral TRB-6S tenor trombone cup mute creates an exciting tonal quality with near-perfect intonation. They are made of spun aluminum and have been tested to perform evenly in all registers. With its unique shape this all-aluminum cup mute produces a smoother richer sound for tenor trombones. Lined with a neoprene rubber rim that eliminates vibrations the adjustable cup will never loosen or drop off. It is easily installed by simply moving the cup up to the desired length for a tight fit. The corks may be reshaped for optimal acoustical placement.