This product is either discontinued or we cannot get that from suppliers.
Poly Plantronics Spare Bt600 Bt Adapter 211249-01, Black, Bluetooth Adapter, External, Device Headset, Host USB Type C.
The Poly/Plantronics BT600 USB-C Bluetooth Adapter 211249-01 is specifically designed to work accurately with Voyager 3200 UC, Voyager Focus UC, Voyager 5200 UC, Voyager 8200 UC, and Voyager 6200 UC.