GROCO 1/2" NPS NPT Combo Stainless Steel Thru-Hull Fitting w/Nut

The GROCO 1/2" NPS NPT Combo Stainless Steel Thru-Hull Fitting with Nut is a critical component for any boater or marine system operator who demands reliability below the waterline. Whether you're installing a through-hull intake for cooling systems, raw water lines, or drain applications, this fitting serves as the foundation of a watertight connection that separates your vessel's interior from the ocean. After years on the water, you learn that through-hull fittings are not areas to compromise—they're the gatekeepers between comfort and catastrophe.

Constructed from #316 marine-grade stainless steel, this fitting resists corrosion in saltwater and freshwater environments far better than standard stainless or bronze alternatives. The combination NPSM/NPT thread design provides flexibility when connecting to various hose barbs, adapters, and pipe configurations—a practical feature when retrofitting existing systems or working with multiple suppliers' components. UL Listed to standard 647B, this fitting meets stringent safety and performance certifications that govern marine plumbing installations. The included nut ensures a secure, leak-free seal against the hull, with the compact 1/2" diameter making it suitable for mid-size through-hull applications without excessive structural modification.

Cruisers, commercial operators, and system builders trust GROCO fittings for their proven track record and consistent performance across freshwater lakes, saltwater bays, and offshore passages. Installation requires careful hull preparation, proper bedding compound, and attention to interior backing nut torque—details that separate a dry boat from a sinking one. This 1/2" size accommodates most standard cooling loops, head discharge lines, and raw water intakes on vessels ranging from 25 to 60 feet. For boaters who understand that through-hulls demand precision and corrosion resistance, the GROCO combo fitting delivers both without question.