Those of us that have had a baby with colic, definitely know all about the long nights of walking up and down the hallway, bouncing your baby trying to get them to stop crying and go to sleep. Dr. Weil kept you in mind when designing the Weil Baby products. All the bottles and training cups are designed with a Airwave Venting System. Made to outperform other venting systems & that has been reached with the moisture locking system. All products are BPA and toxin free. So what's better than know the products you're using and a gas free baby?... A goodnights sleep!