This product is either discontinued or we cannot get that from suppliers.
Poly Plantronics Spare Bundle Neckband 85694-01, 2 Links + Travel Case, Compatible With Poly Blackwire C435, C435-M, Black.
The Plantronics 85694-01 Spare Neckband Bundle is consists of 2 links of durable neckband and travel case that will secure your Blackwire C435 and C435-M headsets.