The Poly Savi 740/745 Neckband (85R32AA) is a headset accessory that lets you wear a compatible headset behind the head. It provides an alternative to an over-the-head headband style.
This neckband is listed for Plantronics Savi W440, W445, W740 and W745 wireless headsets, along with CS540, CS540-XD and CS545-XD models. The listed equivalent part number is 84606-01, which can help identify the accessory in replacement-part catalogues.
The product listing specifies one neckband in the package.