The 241mm O Ring Hatch Cover is an externally sealed hatch cover with a fixed gasket attached to the hull of the boat. The A.638 O ring is placed under the small lip of the gasket and the hatch cover lid is then securely screwed onto the gasket to form a tight seal. This hatch is available in three colours and can be paired with the A-BAG-KIT hatch cover bag for additional storage space. For complete water tightness, the A.638 O ring must be installed on this hatch cover. Please note that the A.638 O ring is not included.