Monaural headset for desk phones 3-in-1 wearing styles: headband, neckband, ear hook Noise-cancelling microphone filters background noise HD voice + Hi-Fi sound for crystal-clear conversation Break-proof, 360° rotating microphone boom (FreeSpin) Luxurious ear cushion and additional cushioning on headband provide for superior wearing comfort A connection cable or amplifier is needed to connect the headset (both options sold separately). Please note that the required connection cable varies by phone.