David Clark model H3312 Ground Support Headset with 25' Cord.

Noise Attenuating Headset

• M-1/DC Noise Canceling Amplified Dynamic Microphone
• Noise Shielded Microphone (Muff) with Momentary PTT (Push to Talk) Switch, Hangs Freely Ready for Periodic Use.
• Soft Headpad and Ear Seals guarantee Exceptional Comfort.
• 25 foot straight cord with PJ-051 plug to meet with series C31-XX extension cords.
• Corrosion Proof, Chrome Plated Headset/Stirrup Assembly
• Certified Noise Reduction Rating of 26 dB.

  NRR 26 dB NOISE ATTENUATION DATA - MODELS H3312 Frequency (Hz) 125 250 500 1000 2000 3000 4000 6000 8000 Attenuation (dB) 22.4 25.5 30.3 33.3 34.1 39.3 39.9 38.7 38.3 Standard Deviation 3.2 3.2 3.0 2.2 2.5 2.6 2.4 2.5 3.5