• For connecting two Plantronics QD headsets to one station for training purposes. 
• It connects via the quick disconnect. Can be used on any headset that has a Plantronics compatible QD on it, does not have to be a Plantronics headset.
• Used for training purposes
• Old part# 27019-01, New HP part# 85S07AA
• OEM HP Plantronics Brand

There are other alternatives that work the same as this cord, but al a lower price point.  

Click link for other alternative