Monaural DECT headset. Connection to the device: EHS adapter, RJ-9. Wearing style: In-ear, wearing style: Convertible/ear hook/over-the-head, wearing mode: Mono. Suitable for: Office, Microsoft certification: No. Microphone with noise cancellation. Wideband audio quality. Up to 9 hours of talk time. The Plantronics CS 540 offers wideband audio quality that enables high-quality communication with your conversation partner. A built-in protection limits the volume to a maximum of 118 dB(A), so you are not disturbed by sudden loud noises. Well connected with DECT technology. The DECT technology, which provides the wireless connection between the headset and USB adapter, ensures a reliable connection with excellent audio quality and a large range of up to 120 meters.