Closed cell is a type of foam in which the “cells” are closed and tightly pressed together, contrasting with the open, interconnected cells of the open-cell, or traditional polyurethane foam variation. This means that water rolls off the foam rather than passing through it. With higher density and greater pressure resistance, this malleable material comes in a variety of forms. From the rigid polyethylene (cross-poly) foam to the less dense EVA foam, and the squishy feel of Flotex, closed-cell foam is a versatile material offering a tight seal and enhanced stability.