Link to the Flip Trainer Kit.
This picture of 3 pads shows how the hook and loop is set up on them so that they are held in place inside the waterproof shell. The second row of loop on one end allows you to fold it down and still attach it inside the cover. This second row is used when the shell is set at the small rise setting on a younger or smaller learner. The insert thus adjusts down to fit and stay put at the smaller rise. See how they work in the trainer shell.