Less resistance for your rebreathing circuits The smooth Y circuit can be used with the Merlin system, Classico Flow, the semi-reusable circuit, and other rebreathing systems. The Y piece and cap are used for leak testing, and its smooth internal PVC lining provides less surface area, resulting in reduced resistance. This circuit is available in two different sizes, 15 mm and 22 mm in internal diameter. Both sizes are 1.8 meters in length. It includes blue connectors which are 22 mm accessories. For patients weighing up to 7 kg, use the 15 mm size, and for patients weighing between 7 kg and 40 kg, either 15 mm or 22 mm can be used. For patients weighing more than 40 kg, the 22 mm size must be used. Please note that the connectors are 22 mm, so do not confuse them with the smooth diameter of the mini type which requires 15 mm connectors. This can be used as a complete circuit for patients as it includes patient hoses, a Y piece, and a cap.