This is the Plantronics Calisto Bluetooth replacement/spare headset (part#77043-02) for the Plantronics Calisto Pro Wireless Headset.  This is the spare headset If you lost or broken your original Calisto headset. This headset is Bluetooth and has a 33ft range to the remote keypad.

This headset can also be used as a standalone bluetooth headset for your bluetooth enabled cell phone.  It can be charged remotely with an AC or Car charger, see accessories below.

Also see Plantronics Calisto FAQ and Plantronics Calisto datasheet