Here at Marine City Hardware, we specialize in marine hardware products. We are all family and are all working together to bring our customers exactly what they need. Our motto is high-quality products and taking care of our customers. Everything is double-checked and electronically tested before being sent out to ensure the highest quality. Our company provides retail and wholesale services so you may also message us if you want to order our products in bulk as well. Our exceptional prices and superior manufacturing company make us the best around for any marine products. the feature is made of 304 Stainless Steel. A: Diameter: 100 mm (4 inches), Thickness: 1.0 mm (0.05 inch).B: Diameter: 130 mm (5 inch), Thickness: 1.0 mm (0.05 inch).Super DurableMade of stainless steel material, durable construction.Stainless Steel Butterfly VentEasy to stall, convenient to use.ApplicationSuitable for related vents in boats, marine, yacht, caravan, home. Help fresh air and sunlight flow in and out of these areas to prevent orders from forming. Commonly use for Marine Companionway Door, Cockpit, Cabin Ventilation, or use for a household shed or additions.