Evenflo Vented Nurser The Evenflo Elan Vented Nurser is the first bottle to offer a one-piece vent system to prevent air bubbles from entering the liquid. The one-piece design is easy to clean and maintain. The Elan silicone nipple is textured for improved latch-on. It features a contoured baby bottle shape which makes it comfortable for parents to hold and offers convenient metric and standard markings. The Evenflo is a preferred brand among nurser bottles.