Mine are the trim delete stock depth bumpers
I put it together with two carriage bolts on each smoothie fiberglass bumper which I probably didn't need
The bolts were to keep foam from pushing the bumper off the frame not to hold it on
They are filled with closed cell expandable automotive grade foam and thats what holds em on.
Been good for over ten yrs at this point
They have fiberglass bumpers now of different depths at CAR