ReSound One hearing aids have been introduced with something that has never been done before - a microphone and receiver positioned inside the ear. This M&RIE (Microphone & Receiver-In-Ear) technology allows patients to collect the whole sound environment, just as nature intended. In addition, these devices also come equipped with Ultra Focus, a patient-activated feature that uses a powerful directional pattern from both hearing aids so patients’ can focus on the speech in front. ReSound One comes in three styles. There is a size 312 battery version, which is the smallest, a lithium-ion rechargeable version, and a size 13 battery version, which is the largest.