Best used as a replacement hatch bag for Prijon brand kayaks previously outfitted with this waterproof hatch bag. Bag is Curved, about 14 inches long. Not a True Hatch Rim! Hatch Bag Rim is 7 7/8 inches in diameter OD, 5 7/8 inches ID. Screw holes are 7 1/4 inches on center, across 6 O'clock to Noon screw. Information on this part and the kayaks it was made for is scarce.FATCAT