This distinctive football-shaped flip-up door twist latch was used on hatches and inspection ports for many years. The original manufacturer went under, but we found a source for them!
The football shape was unique. If the twist latch in your hatches or ports looks like this, then this is the one you need. This one is bright white but a slightly off-white (more common) version was also used. The complete kit includes both sides of the latch, spring, O rings, and assembly instructions.
Dimensions: The latch handle is 2" long from point to point The round base of the paddle on the inside is 1-1/6" diameter The paddle is 9/16" wide