Ultimate Ears In-ear monitors are made to custom fit your ears. The interior measurements of your ear canal are needed in order to construct our product and to adhere to the highest quality and sound fidelity. The only way for us to build your monitors is for you to visit an audiologist and get custom molds made first. Audiologists are doctors that specialize in hearing health and as such they have access to instruments needed to fit their patients for hearing aids. They will have the tools needed in order for you to begin the process of getting your own custom Ultimate Ears In Ear Monitors. You will find these instructions useful to have during your visit to an audiologist: UE Audiologist Instructions