These are special headsets for the Spectralink System. Either the Supra (headband style, model PTH100) headset or the TriStar (earhook style, model PTH200) headset. These headsets are specially shielded to mitigate a buzzing sound which would otherwise occur with standard Plantronics headsets in a Spectralink system. Both the PTH100 and PTH200 (see below) come complete with the necessary connector cord for Spectralink. Nothing else is needed.