A sterile collection of mechanical devices intended to be used with a balloon catheter for a planned intervention to determine the appropriate endobronchial valve sizes for a patient's lung airways (bronchial lumens). It typically consists of a glass syringe and a plastic calibration gauge with holes representing available endobronchial valve sizes. The syringe is used for filling the balloon with a medium (e.g., sterile saline). Using the same balloon catheter, the volume reading on the syringe made with the balloon in the airway is compared against the volume readings taken with the calibration gauge to select the proper valve size needed for an airway. This is a single-use device.