The Plantronics M10 Universal Amplifier is easy to use and works with your choice of Plantronics
 headsets to deliver precise levels of listening and talking comfort, superior protection, and 
excellent audio performance.The M10 includes near-universal compatibility with single- and multi
 line telephones. The Plantronics M10 has ergonomically designed volume control, headset/handset 
selection button and mute control.