MECoral Dosing Caps are designed specifically for the MECoral Gallon jugs.   The fitting accepts standard 1/4 inch RO rigid tubing (tubing not included). The same size used by most dosing pumps.  Cut a piece to fit inside the container so it picks up from the bottom, and run the other end to the dosing pump.   These caps make changing out jugs very simple.   2 caps are included per order.   Do not tighten caps down all the way as air needs to enter the container.