Pro Ears - Pro Hear - Pro Hear IV - Behind the Ear (BTE) - PH4BTE - Digital Hearing Device - Hearing Protection and Noise Amplification - Discreet Aid for Hearing Aid, enhance and protect your hearing with the Pro Hear IV Fully digital signal processing on two channels using push button select. Impulse Sound Suppression set at 85dB. Wind Screen. Adaptive Feedback Canceling. Static Feedback Canceling. Wide Dynamic Range Compression. Gain setting at 17 dB on channel one and 22dB on channel two. Exceptionally low THD at &lt; 2% Typical 120 hour battery life using 312 type battery. Ultra compact size and weight, less than 1/4 oz. One year warranty High Fidelity sound quality. Dynamic Contrast Detection. Adjustable Volume Control - rotational dial. Low battery and program change tones. We only use Ultra - soft comply Foam Tips for a secure, comfortable fit. 10 channel layered noise reduction Fixed Directional Processing Directional microphone.