The Forney 75522 Aro style plug male NPT 1/4-inch X 1/4-inch coupler female NPT Set is made of steel construction. Intended for use on compressed air lines only. Forney Industries is one of America's longest operating family-owned metal working product companies. Founded in 1932, Forney offers more than 5,000 products for the hardware, automotive, farm and ranch and do-it-yourself markets. If you've got metal working questions, we've got answers. Were committed to your success regardless of location size or needs. Aro style plug male NPT 1/4-inch (6.35mm) X 1/4-inch (6.35mm) coupler female NPT set. Max working pressure is 300 PSI. Claims for warranty must be made within 90 days of the date of purchase. Proof of purchase required. This warranty does not cover any product that has been subject to misuse, neglect, negligence or accident, or that has been used in any way contrary to the purpose intended.