big STUFF Gaps & Cracks is a polyurethane-based insulating foam that fills, air-seals and insulates subatomic gaps -LRB- up to 1 inch -RRB- inwardly or out. But you probably as very much from the name. What you might not have guessed is how it is to use or how it expands to take the shape of cracks and voids to form a perdurable, gas-tight, and water-repellent bond that eliminates unloved airflow and helps reduce condensation.