NEVER MISS ANOTHER CONVERSATION. The Hear-Acle™ Sound Amplifier increases the volume up to 35 decibels for crystal-clear hearing. Comfortable, lightweight design and small size make it practically invisible in your ear. Each battery provides up to 75 hours of continuous use. Adjustable volume control. Includes pocket carrying case. Uses one A10 button cell battery (included). Plastic. Replacement batteries available.