Features:-Specially designed for hearing-impaired people, more suitable for the ear canal. Even when used for a long time, there is no pain.-Your hearing aids can be charged using the detachable charging case (you will need to charge the charging case first). -Maximum gain is 117dB, suitable for moderate to severe hearing loss (see hearing loss table).-If the earmuffs are not fully inserted into the ear canal, or if the air leaks out of the earmuffs, it will cause an annoying whistling sound. We offer 3 different sizes of ear tips to reduce whistling and noise.-Super-mini size and light weight for easy carrying.Specification:Colour: whiteCharging time: 4-6hoursWorking time: 20 hoursMaterial:ABS+siliconeVoltage: D C 3.7VModel: Z-19Peak OSPL 90: ≤117dB.