Red Devil. King Kaulk hybrid polymer is a multipurpose caulk, sealant, and adhesive in one. The mildew-resistant formula can be used indoors or outdoors and forms a flexible, watertight seal that won’t shrink or crack, the maker says. Suitable for use as a caulk in kitchen and bath applications; a sealant around windows, doors, and gutters; or for bonding wood, concrete, brick, metals, tile, plastics and more. Available in 10.1-fluid-ounce cartridges. 800.423.3845.