Oatey 30115 Hercules Boiler Liquid Stop Leak, 1-Quart The product is easy to use The product is highly durable and handle The product is manufactured in China Seals and repairs cracks and leaks in steam and hot water systems No odors, no priming, no foaming As the water leaks through the crack, it is vaporized and the oxygen in the air transforms the boiler liquid into a strong, solid substance Contains no petroleum distillates and is safe to use in boilers and systems with plastic or rubber components Tough seal expands and contracts with heat, resists pressure and is not affected by boiler cleaners