Big Stretch is a high-performance water-based elastomeric sealant with powerful adhesion and superior elasticity. It spans gaps up to 2 wide and stretches up to 500% of original joint size without cracking. Big Stretch wont crack÷it just stretches. Stays soft and elastic over time for a years-long, lasting seal. Sticks, even to difficult surfaces. Compatible with a wide variety of building materials, including difficult ones like vinyl windows and siding. No need to search for a product specific to every different surface. No special chemicals required.