Unique twist shape is easy to hold and comfortable Micro air vents help prevent nipple collapse Molded measurement markers in both ounces and milliliters The Evenflo Feeding Classic Bottle delivers a twist on an iconic, classic design. The unique, ergonomic shape is lightweight and easy-to-hold, making feeding time comfortable for both you and your baby. The included Classic Slow Flow Nipples are 100% silicone and feature micro air vents to help prevent nipple collapse. The nipple has a gradual transition between nipple length and base to allow your baby to maintain their latch. Made from BPA-free polypropylene, the Classic Bottles have molded measurement markers in both ounces and milliliters to provide an easy and accurate way to measure the volume of liquid. These dishwasher-safe bottles (top rack only) are compatible with all Evenflo Feeding breast pumps, as well as most other standard neck breast pump brands. The bottles and nipples are 100% free of BPA, polycarbonates, PVC and phthalates, and are also made of FDA-approved food grade material.