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: AG13 CR battery(included). Input noise: =30dB. Voltage: DC 1.5V. Current: =4mA. Max sound output: 130±5dB Sound gain: =50dB. Total harmonic wave distortion: =5%. Frequency range: 300~4000Hz. Operation instruction: 1. Put the earplug on the hearing aid, you can select the appropriate size earplug better for fit in your ear. 2.Open the battery cartridge cover, put int the battery in correct direction. 3.Put the hearing aid in your ear, plug in the earplug tightly(make sure the hearing aid is power off or volume adjuster is in the minimum position, otherwise the instant sound will make you uncomfortable. 4.Adjust the hearing adi body to find a comfortable position. 5.Turn on the hearing aid and adjust the volume to get clear sound. 6.If you want to use the hearing aid with ear hook, please put the ear hook to the earplug connection base, left ear hook and righ ear hook for your selection. 7.If you hear the whistling sound, please check if you plug in ghe earplug tightly. 8.If you stop using the hearing aid, please take out the battery, you save effectively energy.