The new dr browns options range the first convertible bottle that can be used with or without the green vent system r r 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 the relief of wind related colic r r r r as baby becomes more developed the bottle can be used without the green vent system to work more like a