Mule-Hide #251 Premium Wet/Dry Elastomeric Flashing Cement differs from #231 in that it is polymer-modified, meaning it is more flexible and higher-performing in low-sloped commercial applications than #231. #251 differs from #241 in that #251 is formulated for functionality in wet applications, where necessary, and is contains premium-grade polymer modifiers. #251 is the premier repair compound that is easily spread and applied to repair splits, seams, cracks and holes in spudded gravel, mineral surfaced cap sheet, smooth surface asphalt roofs, and most SBS andGranulated APP membranes. The modified properties provide excellent adhesion, elongation and recovery characteristics. Contractors seeking the highest quality, modified asphalt flashing cement with wet/dry functionality choose this product for commercial, low-sloped or steep-sloped roofing applications.