This is a double layer magic dome set of ReSound open-air hearing aid domes with 5pcs. Size is 6mm in small. We have three different sizes which are Small size (6mm), Medium size (9mm), and Large size (12mm). You could find the seven variations in different combinations in the middle side of this page. <br><br> These domes could be used with Resound open-air hearing aids, or Signia, Phonak, Otofonix, LifeEar, Retone, Beltone, Advanced Hearing, Austar, NewSound, Hearing Assist or MD hearing aids. <br><br>These are NOT suitable for RIC models. <br><br> We suggest you to start with the mixed set ASIN# B07HB31CK9, this will help you find the most suitable size for your ear canal. <br><br> If the dome is too big, your ear canal will feel pressure and will not be comfortable. <br><br> If the dome is too small, the sound will be leaked and you will hear a terrible squealing. <br><br> So it's important to choose your suitable size carefully in advance. <br><br> If you already know which size will be suitable for you, then please directly purchase a set with your suitable size.<br><br> Hope you enjoy our products and service. <br><br> We sincerely look forward to your good reviews.