A method for molding an airway adapter, the airway adapter comprising a flow path for fluid and integral windows to allow a measurement path to pass through the flow path, the method comprises injection molding the airway adapter in a single shot molding step. During the single shot molding step, the windows are initially thicker than their final thickness and reduced to their final thickness by moving pins that press the windows to their final thickness. An airway adapter comprises a flow path for fluid and windows for a measurement path through the flow path. The windows may be located on opposite sides of the airway adapter the windows may be integral with the airway adapter forming one solid part of the airway adapter jointlessly and continuously and the windows may have a thickness of less than 0.2 mm.
