This Plastic Mounting plate (made in WA) is designed to be light strong and stiff. Used as a replacement for broken rudder mounts or to replace a heavier third party model
This screws directly into the flush mounted brass threads in the back of Finn kayaks that typically come with a rudder (e.g. Molokai, Endorfinn etc.) Some older models of kayaks may not have these brass insets and will require a different kind of gudgeon mount.
If you require a full rear assembly the best option (easiest & cheapest) is to buy this item and a spirit rear assembly (mounting plate with rudder blade etc.) and swap out the spirit plate. (The Spirit plate is shorter and the holes are closer together they are not compatible even with a drill :))