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. It is 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 or sleep. This reduces colic spit up burping and gas. This helps prevent fluid in the ear. It is easy to clean dishwasher safe. This is BPA free.