Willseal® Coreseal is a lightweight, preformed closed-cell ethylene vinyl acetate (EVA) copolymer foam. It is designed to provide a watertight, dust-proof, airtight, noise-reducing, thermally insulating and UV stable primary seal that does not require invasive anchoring for installation. Willseal Coreseal is engineered to perform in both horizontal and vertical applications. Willseal Coreseal is capable of +/- 25% movement from the mean joint size.