Black Jack Neoprene Super Flash Cement is a unique professional-grade elastomeric flashing and repair product that cures to a durable, long-lasting rubber membrane. This versatile cement remains flexible through extreme temperature ranges and effectively seals leaks on both wet and dry surfaces, even in standing water. It is designed for the construction and repair of all flashing, parapet walls, coping, and chimneys. I for sealing cracks, holes, and tears in built-up roofs, including asphalt, coal tar, and modified bitumen single-ply systems. When applied on composition and built-up flat roofs, any breaks or blisters should be opened and allowed to dry before filling. This product also works excellently for sealing laps in sheet metal roofs and can be used as a patch and repair for EPDM rubber sheets. Please note, it is not intended for use as an adhesive. With an elongation of 250%, it provides flexible and watertight protection for up to 30 years. For results, surfaces must be clean from oil, grease, dust, and other foreign materials before application. It is not suitable for use under roof felts and membranes or for adhering shingle tabs.