Plantronics - S11 System Over-the-Head Telephone Headset w/Noise Canceling Microphone - Sold As 1 Each Connects to single- or multi-line phones with ease. Offers hands free convenience and comfort. Noise-canceling microphone reduces background noise to ensure clear conversations. Universal amplifier is compatible with most phones and provides mute and volume control. Headset Type: Monaural; Headset Style: Over The Head; Earpiece Type: Ear Cushions; Earpiece Material: Foam. Connects to single- or multi-line phones.Hands free convenience and comfort.Noise-canceling microphone.Compatible with most phones; volume/mute control. Includes Universal Amplifier.