The SpecSeal® Window Wall Gasket is a high‑performance intumescent rubber firestop gasket reinforced with glass‑fiber mesh, engineered specifically for edge‑of‑slab firestopping in window wall construction. Designed for simple and efficient installation, the gasket fits between the floor slab and the aluminum framing system, positioned directly behind the slab closure panel to create a reliable fire‑resistant seal. When exposed to fire, the Window Wall Gasket rapidly expands (intumesces) to form a dense, highly insulative char. This char effectively seals the slab edge void, helping to prevent the spread of flame through window wall perimeter joints. The result is a durable, code‑compliant firestopping solution ideal for commercial high‑rise and multi‑story building envelopes.