The Reizen Loud Ear 120dB Gain Personal Amplifier for the hearing impaired is a powerful personal amplifier with a built-in microphone for clear and loud delivery of voice and sound through the single mini earphone. This personal amplifier picks up sound at a distance of up to 100 feet away. Handy built-in belt clip allows you to attach it to your belt or clothing. Estimated battery life - 48 hrs. Frequency- 20Hz - 20KHz. 90-Day Manufacturer's Warranty. Includes 2 AAA batteries and single earphone. Additional earphones are available to use as spares or replacements. Product dimensions (imperial): 2.5 inch H x 1.75 inch L x 0.75 inch W Product dimensions (metric): 63.50 mm H x 44.45 mm L x 19.05 mm W