Behind-the-ear (BTE) hearing aids are housed in a curved case that fits neatly and comfortably behind or over your ear. A custom ear mold is made to the exact shape of your ear. The custom ear mold is used to direct the sound from the hearing aid into your ear and to secure the hearing aid in place.
Open fit hearing aids are similar in style to BTE aids in that a shell sits above your ear and a wire travels down from there into your ear canal, but that's where the similarities end. Open Fit BTEs are much newer technology - the shell above the ear is much smaller and the whole aid is lighter. The earpiece of an open fit hearing aid is a small, soft rubber cap which is much more comfortable than the tightly fitting earpieces of BTEs, CICs, etc.
In-the-ear (ITE) hearing aids are custom designed and fit directly into your ear, filling most of the visible portion of your ear. All of the components are housed within a single plastic shell. They have no external wires or tubes, and are very light in weight.
In-the-canal (ITC) hearing aids are custom designed, smaller in size, and fit more deeply into the ear canal than in-the-ear hearing aids. They have a wide cosmetic appeal because they are less visible than in-the-ear hearing aids. Because they are smaller in size, however, they can only be used by people with mild to moderate hearing loss.
Completely-in-the-canal (CIC) hearing aids are also custom designed. They fit the deepest into the ear canal, so they are the least visible and most cosmetically appealing. The battery life for this style is rather short because the battery is so small. The aid's size can also make it difficult to manipulate, particularly for people who have trouble with finger and hand dexterity (such as from arthritis).