The UE Fits app for Android and iOS connects the earphones to your phone, then walks you through the custom molding process. The eartips are made of photopolymer, a gel that reacts to light. There’s an outer layer of soft silicone that actually makes contact with the ear. The photopolymer is malleable, and once the app triggers the customization process, tiny LEDs inside the earpieces activate the photopolymer gel, and it hardens within 60 seconds. You’ll feel the eartips warming in your ears during this process (not distressingly so), and when it’s all done, you have custom-molded earphones..
Do the eartips feel like custom-molded pro-level in-ears? Not quite, but the in-ear seal is excellent, and there’s definitely a difference between when you put them in before they've been molded and how they feel after the molding process. The translucent eartips still feel soft before and after—it's the internal polymer gel that hardens. The end result isn't as snug as a pair made from impressions taken by an audiologist, which actually enter the ear canal and create a seal that would be near-impossible with this methodology, but this is no gimmick.
