This fitting is perfect for connecting clear tubing to new/first PVC tubing installations with glue recommended on the PVC end. Select inlet and outlet diameters according to installation. Inlet : clear PVC tube Ø 6 or 10 mm (1/4'' or 3/8''). Oulet : PVC tube Ø 21 or 40mm (1/2'' or 1 1/4'')