Plantronics M655 Bluetooth Headset with Pocket Charger Features 128-bit encryption for secure and private calls with a range of 33' Digital Signal Processing (DSP) enhances the incoming voice and removes impurities from the audio signal Dual wearing styles: in-the-ear gel or ear hook for a secure and comfortable fit Pocket case vibrates with incoming call when headset is on mute Up to 3 hours talk time and 80 hours standby, Compliant with Bluetooth v2.0 devices