The Model H10-56, designed specifically for helicopter use, has the best noise attenuation with a Certified Noise Reduction Rating of 27 dB. Flo-Fit Gel Ear Seals Hinged wire boom with the M-101 amplified Dynamic microphone Conforms to MIL-M-27291A Coil Cord (5' extended) with U-174/U Plug 5-Year Guarantee