Stainless steel deck fill replacement cap and chain 66061-3 fits Attwood deck fills with a 3.5” flange size (66411C1 Gas, 66412C1 Diesel, 66126C1 Waste). The cap is a high-polish, enhanced 316 stainless steel with a key slot for opening and closing. An O-ring helps keep the cap watertight when secured. Attwood Corporation has been an award-winning leader in engineering, testing and manufacturing the highest quality marine products for over 100 years. We deliver safe and reliable lighting, fuel systems, water systems, seating & pedestals, swim ladders, custom upholstery and general marine accessories that are easy to install and meet regulatory compliance.