The housing of this hearing aid completely fills the ear. The advantages include a longer battery life, the availability of a power version for severe hearing loss, and improved operation.
This is a small and discreet model. The hearing aid housing sits in the ear canal, thus only filling half of the ear.
This used to be the smallest model, the CIC offers the ultimate in discretion and typically have a nylon strand to help the removal from the ear.
This subgroup of CIC devices are hearing aids that are worn deep in the ear canal and are often completely invisible. Phonak's Titanium is an example of an IIC hearing aid.