Willseal® 250 is a pre-compressed, self-expanding open micro-cell polyurethane foam impregnated with a hydrophobic, acrylic polymer sealing compound coated with a factory-applied silicone sealant. 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.