J-B WELD® water pump and thermostat housing gasket maker and sealant is a specially designed RTV (room temperature vulcanized) silicone gasketing material for use in mechanical assemblies. Curing occurs with exposure to moisture in the air, forming a tough, waterproof, petroleum and weather-resistant gasket and seal on most surfaces. This product is grey in color, will not shrink or crack, is sensor safe, has good temperature resistance up to 500 deg F intermittent and is great for many automotive applications.