Hey Carlos, while mine are still installed and in mint shape, I would imagine they would need to be adhered to the floorpans? I don't think the repo's come with adhesive such as the aftermarket sound deadener like Dynamat. As these will be an underlayment, if you used something like 3M's super Trim Adhesive (spray glue) I would think that would be enough. They are pretty form fitting and won't see much movement over all...

Later - Brett!