9 out of 10 healthcare professionals recommend Dr Brown's Natural flow bottle for Colic relief. The patented internal vent system creates a vacuum-free environment which eliminates the vacuum and air bubbles found in most baby bottles making feeding with this bottle closer to breastfeeding. It allows air to enter through the teat collar, without being incorporated into the breast milk or formula. The air is then channelled through the internal vent, to the area behind the feed. The design of the bottle will help to reduce colic, while the vent system eliminates the negative pressure and air bubbles which also reduce burping and wind. Over half of those changing to a Dr Brown's Natural Flow baby bottle saw an improvement in 3 feeds or less, outperforming any other brand. - Results of HCP Colic Survey carried out by Consumer Analysis Ltd - May 2010 The Dr Brown's Options Starter Pack provides excellent value for money. This pack includes: 2x 150ml Bottles. 1x 270ml Bottle. 2x Level 2 teats. 2x Level 3 teats. 2x Bottle brushes