Backed by Attwood's trusted Lifetime Warranty! Why specify plastic parts when these fittings will last the life of the boat. The scupper flap is tough neoprene rubber with a molded V that fits into the grooved body to reduce back wash. Fastners are concealed and corrosion-proof. Lifetime warranty.. Rugged Stainless Construction. Cast from certified enhanced 316 Stainless Steel for strength and lifetime corrosion-resistance.. We polish all visible areas to a mirror finish, then each part goes through a passivation for additional protection. Thick steel sidewalls withstand continual stress and hose flexing. Caution: Thru-Hull connectors are designed for installation above the water line only