Equipped with productive active anti-noise transmitter-receiver headset factory and company, Fenghuo Hongsheng is one of the leading China wireless earphones manufacturers and suppliers. Welcome to contact us. Model OSDK-12 Active Anti-noise Transmitter-receiver Headset which adopts the structure of binaural head ring is the audio terminal for the pilot. The product adopts Active Anti-noise Technology so that it can enhance the voice communication articulation in the high noise environmental condition.The pilot's audition is protected availably. It has obtained CTSOA (Serial Number: TSOA0034-XB-002) which is awarded by Civil Aviation Administration of China. It can replace the foreign products.  Main Technical Specifications:  Frequency range:200Hz～4000Hz Power supply voltage: (9±3) V DC  Operating current≤50mA   Transmitting average sensitivity: (-33±4) dB/Pa   Receiving average sensitivity: (90±5) dB/mW     Average sound insulation of earmuffs≥25dB (300Hz～8000Hz)   Active anti-noise sound insulation amount:Max≥12dB;Min≥6dB (50Hz～300Hz)  PS:The transmiting sensitivity can be adjusted according to the requirement of the user; the earphone can be also used in single track or double tracks; It also has the volume-regulating function.The transmitter-receiver impedance can choice 75Ω,150Ω,300Ω,600Ω,etc.