After you pour Drano Dual-Force Foamer into a drain, the two ingredients combine to form a powerful foaming clog remover. The foaming action fills the pipe and thoroughly clears its walls, dissolving gunk. A blast of hot water flushes away what's left of the clog. Clogs happen, but with Drano Dual-Force Foamer Clog Remover, you and your drains are unstoppable.