FLOWABLE: Designed for filling narrow cracks with maximum width of ¼ in. (6 mm) to a maximum depth of 6 in. (150 mm). MULTIPURPOSE: Repairs cracks in foundation, concrete, and brick, stops air and water leaks, bonds and seals EASY TO USE: Shake, caulk, and go BLENDS IN: Goes on black, dries gray to match surfaces FAST-DRYING: Dry in 1 hour Rapid Patch Hairline Crack Repair is a two-component, low-viscosity, 100% solids, urethane repair product designed for filling cracks in structural materials including concrete and bricks, for the purpose of bonding and sealing them. Product goes on black and dries gray. Designed for filling narrow cracks with maximum width of ¼ in. (6 mm) to a maximum depth of 6 in. (150 mm).