150ohms speaker, to ensure the perfect voice quality. Noise proof microphone, to increase the voice clarity. Comfortable wear, compact appearance, human engineering design, Can be uninterruptible using.The headset clip can be stretched freely and comfortable wear. Compatible for the most telephones in call center. Superior quality sound with the flexible adjustable noise cancellation microphone. Just plug directly into your headset-ready telephone! You just simply plug this modular plug into the headset jack on your phone and it's ready to be used.