Mini Digital Hearing Aid Features: 1. Good performance:Help you hear the sound clearly and loudly, whether indoors or outdoors. 2. Comfortably fits:behind the ear and can be used in either left or right ears. 3. Battery design: This sound amplifier has built-in battery, low current and power saving. 4. Energy-saving: With the on&off switch, it is energy saving at the furthest. 5. Sound amplifier: It is a good choice to use this sound amplifier for you can feel free to adjust the volum whenerver you are watching plays& TV seeing films, attending a meeting or having a leon. This sound amplifier is ideal for listening to TV, cinema, theaters, live music, etc. Specifications: Max sound output: 1105dB Sound gain: 30dB Total harmonic wave distortion:10% Frequency range: 300Hz-4000Hz Input noise:40dB Voltage: D.C.1.5V Current:4mA Size: sound amplifier:26*15*19mm(L*W*H) Package Included: 1 * sound amplifier 3 * ear cap 2 * battery 1 * brush 1 * manual Notes: 1. Please allow 0-1 inch error due to manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from real object.