5/8 Outer Diameter x 3/8 Outer Diameter Lead-Free Compression Reducing UnionThe 5 8 Outer Diameter x 3 8 Outer Diameter Lead Free Compression Reducing Union is a plumbing fitting used to connect two pipes or tubes of different outer diameters (OD) securely without the need for soldering, welding, or adhesives. The OD specification means it reduces from an outer diameter tube. Specification Details TYPE Lead Free Compression Reducing Union DESIGN Union style allows easy disconnection and reconnection of pipes. MATERIAL Brass