Leak Stopper Rubber Flexx Sealant is a convenient spray patch and repair sealant that dries black. This multi-purpose product allows for quick repairs across a variety of surfaces. The rubberized finish stays flexible to withstand a range of temperatures.Just point and spray to make basic repairs on wood, asphalt roofing, metal and masonry surfaces. Rubber-Flexx is ideal for a variety of roof surfaces including: Shingles Metal Roofs Chimneys, Skylights, Gutters, Pipes, and many other surfaces.