A revolutionary advancement in roof patching and repair. This long lasting rubberized repair is specially formulated to penetrate deep into damaged areas and stop 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 will stop problem leaks for good. Product formulated to be used year round. Leak stopper is ideal for a variety of roof surfaces including Shingles, Built-Up Roofs, SBS Modified Roofs, Metal Roofs and many other surfaces.