Black Jack Rubr-Seal Rubberized Roof & Flashing Cement is our best quality roof cement. This highly flexible product can be used year round in any weather condition to stop and seal leaks. This high performance product provides an exceptionally long lasting seal, formulated to repair cracks, seams and holes in roofing materials. It is also designed to be used in new construction and in setting flashings, drip edges and other roofing edges. It seals and provides a rubberized layer of waterproofing protection. Dries black.