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. The Dr Brown's Options Newborn Gift Set provides everything you need to feed your newborn baby. Dr. Brown's Options bottles work with or without the internal vent system in place. The vent system continues to create 100% vacuum-free feeding, and is clinically proven to help reduce wind related colic. As your baby's feeding develops the options bottles can be used without the vent system to work more like a conventional, teat-vented bottle. Level 1 teats are already supplied on each bottle. This comprehensive set consists of: Microwave Steriliser with Tongs 3 x 270ml Bottles 2 x 150ml Bottles 2 x Level 2 Teats 2 x Level 3 Teats 1 x Bottle Brush 3 x Cleaning brushes 2 x Travel Caps