AXON F-137. Suitable for leisure and entertainment. It's a BTE hearing aid good for the hearing losing people. A good choice if you want to hear better of the world. Can help you hear clear and loud sound when you watch movies, attend meetings or have classes. Specification: Material: Circuit board and Plastic. Color: Black. Battery: LR44 CR battery (included). Input noise: =30dB. Voltage: DC 1.5V. Current: =4mA. Max sound output: 130±5dB Sound gain: =50dB. Color: As the picture shows. Total harmonic wave distortion: =5%. Frequency range: 300~4000Hz.