SH300 Over the head, Monaural Headset, Noise Cancelling Mic. Independent double-sided headband adjustment and ergonomic side support for individually preferred positions and maximum comfort. Noise Canceling blocks out a great amount of ambient noise, making your voice easier to understand. Ideal for professionals who need to keep in touch with what is going on around them and for extended periods of use. SH 300 series headsets are the stylish and high-quality solution for users who value extremely high comfort and top speech quality.