The Gardner-Gibson Leak Stopper Rubberized Roof Patch is a revolutionary advancement in roof patching and repair. This long lasting rubberized repair is specially formulated to penetrate into damaged areas and stop roof leaks instantly! The secret is Penetrex, a unique penetrating oil that reaches deep into the crack and forms a complete seal. with the addition of liquid rubber, this flexible, high performance plastic cement provides a superior watertight bond that stops problem leaks for good.