Mule-Hide #231 Flashing Cement differs from #241 and #251 in that it is a non-modified flashing cement. This product is easily spread and used to repair leaks, cracked spots, and holes in shingles as well as polymer-modified bituminous roofs (APP, SBS). Contractors seeking a refined and premium, non-modified asphalt flashing cement choose this product for all residential or commercial, low-sloped or steep-sloped roofing applications.