Medium size Scupper One-Way Valve, 1 3/8 in. dia. Designed to keep water from entering up from the scupper holes AND will let any water drain out of the cockpit seating area. One size only!
See the OK SIZE CHART to find out which Ocean Kayak models this scupper valve will fit, search for size MEDIUM. (Valves of other size holes are not available at this time.)
The rubber flap from this valve is an exact match to the same rubber flapper valve found in Hydra Adventurer scupper drains. See How To: Hydra Adventurer Scupper Drains. The flapper valves (aka Umbrella Valve) are not sold separately. The rubber Umbrella Valve can be gently removed from the OK valve assembly and fit into the cross hairs of the Hydra Adventurer scupper drains.
The OK Scupper Valves can fit some other brands of sit-on-top kayaks. You will have to measure your scupper hole diameter. The Scupper one-way valve medium is 1 3/8 inches in diameter. 2.5 inches tall. (aka 07.2000.0582)