Dr. Brown’s Natural Flow baby bottle was invented by a doctor and tested on his own children when they were babies, so you can rest assured that this product is as safe as it is effective. This revolutionary baby bottle features a patented “no vacuum” design. It helps colicky babies settle down/sleep and reduces colic, spit-up, burping and gas. This also helps to prevent fluid in the ear/no vacuum. It is easy to clean, and dishwasher safe. Includes 3-8oz Wide Neck Bottles; 2-4oz Wide Neck Bottles; 2-Extra Level 2 Nipples; 2-Storage/Travel Caps. BPA free. While the Bottle Brush has been designed for use with all standard and wide neck Dr. Brown’s Natural Flow baby bottles. It features a combination sponge and bristle brush head for thorough, easy cleaning of all Dr. Brown’s baby bottles. It has fixed chevron channels at the base of the Bottle Brush, which are designed specifically to clean nipples with ease.