Equipped with productive earplug transmitter-receiver factory and company, Fenghuo Hongsheng is one of the leading China cordless headphones manufacturers and suppliers. Welcome to contact us. Model OSE-4 Earplug Transmitter-receiver integrates the bone-conduction transmitter, the receiver, with the earplug. It is the ideal audio terminal for portable communication equipments. This product has the features of small size, light weight, anti noise, etc.. Main Technical Specifications: Frequency response range: 300Hz～3000Hz Operating voltage: DC5V Transmitting sensitivity: (-19±3)dB/Pa Receiving sensitivity: (93±3)dB/mW Receiving impedance: 32(1±15%)Ω Operating temperature: -25℃～+55℃ Weight ≤150g