Dr. Browns Options bottles works with or without the internal vent system in place. The vent system continues to create 100 per cent vacuum free feeding that is clinically proven to help reduce wind related colic. As babys feeding becomes more developed the bottle can be used without the vent system. The bottle works like a more conventional, teat-vented bottle, providing ease and convenience for parents. Capacity 270ml. 2 pack. BPA free. Anti-colic. Wide neck bottle. Variable flow teats. Dr. Browns options bottles - same trusted bottle, now with added benefits. Dr. Browns options is the first convertible bottle that can be used with or without the green vent system. The unique internal green vent system continues to create 100% vacuum free feeding, which is clinically proven to help reduce wind related colic. This is what makes 9 out of 10 healthcare professionals recommend dr browns for colicky symptoms. As baby becomes more developed the bottle can be used without the vent system to work more like a conventional, teat-vented bottle.