Button Head Coupler, for 7/8" Button Head Fittings 1/8" NPT (F). Specially Designed for Button Head Grease Fittings. 1/8” NTP Female Inlet. Recommended Working Pressure: 3, 000 PSI. Maximum Operating Pressure: 4, 500 PSI. Zinc-Plated for Maximum Protection against Corrosion. Lumax is a manufacturer of lubrication and fluid management products. Our products, including grease guns, manual and electric pumps, funnels, drains, grease fittings, filter wrenches, and accessories, are built to the highest standards and incorporate many proprietary features. Lumax's mission is to provide professionals and consumers with innovative and high-quality products to get the job done right. Product development at Lumax goes beyond the physical product, to a deeper understanding of the end-users' needs. Engineered with the "user-in-mind, " Lumax products are built to the highest standards and incorporate many unique features that make work easier, faster and cost-effective. We have a passion for the design process. We listen to our customers and their ever-expanding requirements. Our unique products lead the field in design, quality, and performance.