This is a Yamaha PM5 Silent Brass mute only for tenor or bass trombone. The mute has an interior microphone. A cord with mini-plug is included. Works alone or with the original Yamaha ST9 Personal Studio. New old stock.
The newest version of the Yamaha Silent Brass does not fit bass trombones. This older mute does fit, but also be aware this product is "mute only", without the "Personal Studio" or headphones.