Dr Browns Narrow Neck 250ml Options + Bottle includes the new vent system which is designed to grow with baby. Options + allows you to remove the vent when baby is old enough. Many parents begin by using the vent system and then stop as their babys feeding habits develop. You might begin experimenting around 6-7 months. If baby shows any signs of discomfort during or after the feeding, use the vent system for another month or so, then trying again. Your baby will give you cues that you can try removing the vent system, including a reduction in colic, reflux and gas; consuming more milk, more quickly.