This product is either discontinued or we cannot get that from suppliers.
Poly Plantronics Encorepro 203442-01, Monaural, Boom, EncorePro 500, FF Supra-aural, Sound Mono, Host Interface USB, Wired.
The EncorePro 500 USB Series is a fully integrated audio solution that enables users to focus on every conversation with all-day comfort, built-in call control, advanced audio processing and an enhanced noise cancelling microphone.