It is a lever similar to a see - saw that the user usually stands on with the left and right foot at opposite ends of the board. (dreamseasurfcamp.com)
I guess I would have to remove the existing trim but then ends of boards will show. (theletteredcottage.net)
It's attached to one end of the board while the other end is comfortable fastened to your leg. (odysseysurfschool.com)