Series 6000 Headsets connect to the Series 6000 PTT two-way radio adapter. Headset models should be selected based on the style and features best suited to your application. Headsets are designed for comfort during long periods of use, durability to stand up to rugged use in harsh environments and reliability to provide clear communication for a variety of applications. Heavy duty, 4-conductor cord assemblies are RFI/EMI shielded. All headsets, except single ear and slotted dome models, have noise reduction rating (NRR) of up to 24 dB.