The Forney 75322 Tru-Flate style 3/8-inch X 1/4-inch female NPT plug is steel construction. Forney airline accessories are 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. Tru-Flate style 3/8-inch (9.53mm) X 1/4-inch (6.35mm) female NPT plug. Max working pressure is 300 PSI. Proof of purchase required. neglect, negligence or accident, or that has been used in any way contrary to the purpose intended.