Ideal for use in a drip irrigation system to control or shut-off water supply to micro pipe. Works well as a coupler between lengths of 4mm internal diameter feeder hose by simply pushing the barb into the end of the pipe. When used with supply pipe, use a hole punch to make the proper hole in the tubing. Excellent when watering garden boxes, hanging baskets, flower pots, and vegetable gardens. No glue or lubricants are required. You will find a number of ways to use this handy little in-line valve. The valves fit micro pipe with an internal diameter of 4mm.