Features: l High quality invisible hearing aid sound amplifier l Super mini size and light weight, not easily to be seen l Adjust volume to the minimum before wearing l Increase volume gradually to avoid sudden increase in sound l Convenient for watching movie, enjoying the drama, attending meeting, or having class, it could help you hear the sound clearly and loudly Specification: l Type: K-188 Hearing aid l Mini ITE Hearing aid l Max Sound Output: ≥110 dB ± 5dB l Max Sound Gain: ≥30 dB ± 5dB l Frequency Range: 300～4000Hz l Input Noise: ≤40 dB .