There are three main types available for those experiencing hearing loss: behind-the-ear, in-the-ear, and completely-in-canal. Behind-the-ear are the most powerful as their larger size allows for a bigger battery and circuitry. They rests behind the ear with a short tube connecting to an earpiece placed in the ear canal. https://sanjanacmi.livepositively.com/hearing-aids-devices-that-can-improve-your-ability-to-hear/new=1