Product description H91N Encore Monaural Noise Canceling Headset with Boom MicrophoneliTop-of-the-line model that offers all-day comfort and superior sound qualityliLightweight over-the-head single earpiece design for comfortable extended-wear useliQuick Disconnect feature lets you walk away from the phone while still wearing the headsetliNoise canceling microphone improves voice clarityliTone controlliAdjustable clothing clipliClick-stop headband and turretliSound Enhancement System (SES)liSupports SoundGuard Plus and Call Clarity technologiesli2-year warrantyliRequires Plantronics amplifier to connect to your telephone (not included) From the Manufacturer This top-of-the-line headset model offers all-day comfort and premium sound quality, owing its performance to Plantronics' unique Sound Enhancement System. A tone control switch lets you select the level of bass and treble that you prefer for a full, rich sound. The company paid equal attention to fit and all-day wearing comfort. Encore features super-soft ear cushions, a "click-stop" adjustment system on the headband, and a turret that provides exactly the right fit and consistent positioning of the microphone. The model also features a quick disconnect function that lets you walk away from the phone while still wearing the headset, along with a noise-canceling microphone that improves voice clarity. The set comes with a two-year warranty. Features: Single earpiece headband style Noise-canceling microphone Adjustable Soft ear cushions for all day comfort Flexible boom Tone control