This package includes the Yamaha PM6X mute, the STX-2 receiver, a set of earbuds, batteries and all of the cabling you’ll need.While brass players have always had practice mutes, they were always tough to play with and sounded horrible. Yamaha then came out with a system that allowed players to plug headphones into the mute so we could hear this amazing sound while those around us couldn’t hear much at all. It was revolutionary for people who lived in apartments, had young children or wanted to warm up backstage. The Yamaha Silent Brass was a big success. There have been two major upgrades to the original design.