Pack of wide neck glass bottles, Options+, 150 ml, Dr. Browns (includes: 2x 150ml wide neck glass bottles, 2x level 1 silicone teats (0-3 months), 2x internal ventilation systems consisting of 2 parts each, internal system cleaning brush, instructions) . Can be used with or without the ventilation system. Recommended to be used with the internal ventilation system, for to benefit from the advantages of the fully ventilated bottle: -eliminates vacuum and air bubbles to help reduce colic, expectoration, belching and gas. -eliminating negative pressure can help reduce fluid build-up in your babys inner ear. -keeps the nutrients in the milk -positive pressure design mimics breastfeeding and is ideal for both breast milk and formula.