This product is either discontinued or we cannot get that from suppliers.
Poly Plantronics Blackwire 87506-11, Wired Headset, Connects PC via USB, mobile phone or tablet via Bluetooth, Compatible with Windows® or Mac OS, Talk time Up to 10 hours, Standby time up to 10 days, Listening time up to 6 hours (A2DP), Wireless frequency Bluetooth v3.0 + EDR.
The Plantronics Blackwire C720-M headset connects to your PC and mobile phone – combining the comfort and durability of corded with the freedom and flexibility of wireless.