The Flex-Drain 4 inch x 21 inch polypropylene connector is ideal for repairing damaged sections of pipe. This connector can expand to 21 inch and has flexible construction to create angles with ease. Flex-Drain helps you get the job done faster and easier, with professional grade durability and more versatility than traditional corrugated pipe. Flexible and expandable, Flex-Drain easily bends around any obstacle, hold its shape during installation and with a simple snap, its integrated soil-tight fittings lock securely and stay connected during backfilling. Flex-Drain is a complete drainage solution system that's widely compatible with virtually all traditional 3 inch and 4 inch corrugated pipe and 4 inch PVC. Technologically superior, it's made with no-break copolymers and exceeds all applicable ASTM crush standards.