 Plantronics .Audio 20 Plug 'n' Play monaural headset with a high quality, noice cancelling microphone. Plugs into sound card. |  Plantronics CHS142N Monaural headset with detachable head-band and in-line volume & mute controls. Single 2.5mm jack suitable for IP phones. |  Plantronics H251N Supra Plus Top of the line monaural Plantronics headset with noise cancelling microphone. Suits Polycom IP phones. |
