Series 7000 Headsets connect to the Series C7000 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. All headsets, except single ear and slotted dome models, have noise reduction rating (NRR) of up to 24 dB David Clark Company offers a variety of headsets and communication systems for military ground support personnel for use in ramp operations, deicing, push-back and maintenance applications - in both wired and wireless system configurations.