J-B Weld Hi-Temp Silicone Gasket Maker and Sealant Red, 85g, is a RTV (Room Temperature Vulcanized) Silicone gasketing material. Designed for use in mechanical assemblies where the existence of higher, continuous temperatures up to 287°C (550ºF) or 343°C (650ºF) intermittent might exist. Upon curing, which occurs when the product is exposed to the moisture in the air, the silicone forms a tough, waterproof seal on most surfaces. It will not shrink or crack, resists weathering, is sensor safe and is great for many automotive applications.