Gorilla Filler is a weatherproof expanding foam that seals gaps and cracks in stone, wood, metal, and brick. Its expanding formula creates an airtight, waterproof barrier ideal for both interior and exterior work. Perfect for rough surfaces, cavity filling, and general DIY repairs. One 500ml can covers multiple applications with minimal waste. Hardens to a rigid finish that can be sanded, shaped, and painted for a professional result.