Monaural headset for a desk phone, including adapter for PC/notebook 3-in-1 wearing styles: headband, neckband, ear hook Ultra-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 Connecting the headset requires a connection cable OR amplifier Neither option is included and both must be ordered separately. Please note that the required connection cable varies by phone.