The reducing hose barb union is used for connecting a hose to a hose threaded of a different size, they has barbed ends to create a tight seal on a hose when used with a hose clamp ( included). The union is made of brass for greater strength.They are used in patio, lawn garden hose connect, Irrigation, lawns, air compressors, automatic manufacturing operations, aircraft controls, and tire installation in industries including agriculture, mining, road construction, firefighting, and aviation