These receivers are for the new Widex Rechargeable Moment hearing aids.
Size: They come in sizes 0, 1, 2, 3, and 4 with 0 being the shortest and 4 being the longest.
Power: There are two powers, M for mild-moderate hearng loss, and P for moderate to severe hearing loss.
Your current receiver shoud specify the power and size on the silver part that goes in your ear. Sometimes it rubs off, if you are unsure you can always send us a picture or check with your audiologist!