Replacement Cat Bag style hatch bag for types of six-inch deck plate style hatches that are molded with a bag rim. Use for some older Ocean Kayak, Necky and Aquaterra and Perception kayaks. It may not work all hatches. Fits: Viking, Beckson and Sea-Lect 6 inch screw hatches. Can be used to replace Viking Fat Bags, as seen in small photo to the right, Cat Bags (long and skinny). Outside diameter of the bag ring is 6 inches. Bag is 10 inches deep. The bag ring needs to rest on an internal rim about 5.5 inch inside diameter. Bag is not water proof. FATCAT