Equipped with productive neck ring transmitter-receiver factory and company, Fenghuo Hongsheng is one of the leading China cordless earbuds manufacturers and suppliers. Welcome to contact us. Neck Ring Transmitter-receiver is composed of the bone-conduction transmitter, the air-conduction receiver, the neck ring, the sound conduction pipe, the earplug, the cable, and the plug. It is small in size and convenient to wear, and has the performances of anti vibration and shock, saltfog-proof, and rain-proof; it is suitable for individual soldier and fireman.   Main Technical Specifications: Frequency response range: 200Hz～4000Hz Transmitting impedance: 300(1±30%)Ω Transmitting sensitivity ≥5mV/0.316g S/N≥18dB Receiving sensitivity: 300(1±30%)Ω Receiving impedance ≥90dB/mW Operating temperature: -40℃～+55℃  Weight ≤100g