DuoFoam is an underlayment that laminates polyethylene film to our PolyFoam underlayment to create a vapor/moisture resistant barrier, making it more suitable for installations over concrete. For a quick and easy installation, DuoFoam with Self Seal has an overlap of film on one edge, with a peel and stick tape strip along the other, making it a very installer-friendly underlayment that reduces installation time. DuoFoam with Self Seal also laminates film to both the top and bottom of the underlayment, for twice the amount of protection.