Marine Grade 316 Stainless Steel 180 degree flush mount 4" x 1" Hatch Hinges for boat, RV Constructed of stamped corrosion-resistant 316 stainless steel. Polished to a beautiful, mirror-like finish. Salty Reef Marine Hardware Dependability Trusted by Boaters World Wide and USCG Approved Salty Reef Marine Hardware is an American company trusted worldwide for its durability and dependability. The marine grade hinge is stamped from AISI 316 stainless steel will provide years of service and a bristol shine for the discriminating yachtsman.