This Bung Plug includes the Male and Female Threads and suits most kayaks that come with a similar system where you have lost or broken one of the sections.
The hole Diameter (in the boat not inside the female part) is 25 mm
Matching up the thread on a missing bung Plug is painful especially if the kayak is at all old when it is likely the bung is no longer in production if you get it wrong they will leak so it is safest to replace both parts at the same time.
Note that Wavesport, Dagger, Wilderness Systems, and Perception Kayaks (those with bungs) are threaded into the boat directly with no separate female part. It is best to buy that bung plug as it is still in production and easier to just screw it on than get out a drill etc.