Blackwire 300 Series P/N: 85619-02C320 (Bulk Product) (Stereo). Enter UC with the best-featured headset you never thought your budget could afford. Blackwire 300 Series USB headsets are a simple-to-use, comfortable, and durable choice for conference calls, Web-based training, and PC multimedia applications. Inline controls make it simple to answer and end PC calls and control volume and mute. The lightweight metal headband provides durability while delivering a comfortable and secure fit, while the unique Dynamic EQ feature optimizes sound quality and adjusts settings on the fly, creating outstanding sound for voice, music, and multimedia.