Custom hearing aids are best suited for people with mild to profound hearing loss and come in a variety of sizes.  They take advantage of the shape of the ear to provide great acoustics, directionality of sound and excellent hearing aid retention.  They are molded to fit the client's ear, therefore, providing a comfortable fit. Because these hearing aids sit in the ear, clients can continue to comfortably use headphones.  The size of the hearing aids is depending on severity of hearing loss and customer needs. Some manufacturers offer this style in rechargeable technology.