Poly CS540A Convertible DECT Headset delivers professional performance so you can get more done even when you're on the move. Noise-canceling mic reduces background noise interruptions, ensuring great audio quality. SoundGuard acoustic-limiting technology protects against acoustic shock (AS) by limiting sounds to below 118 A-weighted decibels for your listening comfort and protection against audio spikes. DECT technology allows better audio quality and eliminates interference from Wi-Fi networks so calls stay safe and secure. Choose between narrowband audio to extend talk time or advanced wideband audio for high-definition voice quality. Enhanced Digital Signal Processing (DSP) provides more natural sound, delivering clear audio the way it's intended to be heard. Roam confidently up to 400' from the headset base. Conference up to four headsets on a single base to easily collaborate. Convertible design features three wearable options.