K&W 401224-6 FiberLock Head Gasket & Block Repair - 32 Fl Oz Easy Pour and Go Formula! Permanently fixes head gaskets, engine blocks, cooling systems, and cylinder heads. "Contains 3 unique technologies. Military-Strength Fibers create multi-layer repair over cracks with a web-like weave. Nanotechnology permanently fixes the smallest cracks and crevices. Cool-X Conditioner  lowers operating temperature as it circulates through cooling system." Seals larger holes with less fluid loss than competitive products as proven by lab test (ASTM D6107) Works with all antifreeze or plain water.