Pairs the Plantronics SupraPlus SL H351N headset with the Plantronics M22. The Plantronics? SupraPlus? sets new standards in all-day comfort and reliability for telephone professionals. Enhanced audio quality, flexible boom and stylish design provide greater headset flexibility. The M22 Amplifier connects the SupraPlus SL H351N headset to just about any modular single- or multi-line phone, and offers easy to use volume, headset/handset, and mute controls.