Several kayaks are using adjustable foot rests. But it is quite easy to either break one, or loose one. Here is a replacement part. The slot it slides into is...Show more 27x3mm.
Assemble using a bit of CA to lock the pin in place.
Press on the level to move the foot rest/pedal to the required position. Once you release the level, move the pedal back and forth to get it to lock into place.