Yamaha Silent Brass STX-2 While the mute itself shows no noticeable scratches, there are several scratches on the control unit. Please refer to the photos for details. Operation has been confirmed to be in good working order. No box included. The following is an excerpt from the Yamaha website: "Brass Resonance Modeling" is Yamaha's unique digital technology that cancels out the muffled sound of a mute and reproduces the original sound without a mute. By combining the Personal Studio STX-2 and a compatible pickup mute, the player can perform while listening to a realistic sound as if they were not using a mute. By connecting the output of an audio player or smartphone to the AUX IN terminal of the Personal Studio, you can enjoy karaoke performances (minus-one performances) with music playing in the background. You can also connect the output of the PHONES terminal to a recording device to record your performance.