The New Pig Mildew Resistant Absorbent Sock stops leaks, spills and condensation from spilling into walkways. It can also be placed on windowsills or in doorways to trap rain or snow melt before it enters the building. Unlike cellulose-filled absorbent socks, this 100 percent polypropylene skin and filler resist the growth of mildew. The sock is available in two color options: yellow for high visibility or blue to blend in with the surroundings.