Specification : Max sound gain of 48dB N-H Switch Volume Control Battery compartment ON/OFF switch Use high intensity and long life-time military fiber wire Main Unit Size 4.5*4.2*1cm, NW:7.5g Different size noise prevention earplug Vibration proof box, Battery type: AG13 or A675 (Zinc Air Battery) Max sound output: 127±4 dB Max Sound Gain:: 48dB ± 5dBH