Expect to need two of these per seat. Get TWO for the best results. 

Best used as a replacement for a seat hinge that has failed. Common on classic kayaks such as those by Necky and McNulty. 

This is flexible plastic panel, 3.5 inches by 3.5 inches 3/32 inch thick.

Drill your own holes. Re-use your Hardware if possible. Easy to cut with a utility knife.