Introducing the Infratech 18 2305MG 61 in. Flush Mount Frame - 61.25 x 8 x 18 gauge 304 SS in. - Stainless Steel Marine Grade Color. Now you can enjoy even longer-lasting durability for flush mount installations in climates with exposure to saltwater and other extreme elements by choosing Infratech’s new Marine UpGrade. It combines the seamless look of flush mount installation with our most durable, corrosion-resistant 316 stainless steel construction.