Thermostat housing seal are designed to prevent the ingress of water, dust and other contaminants into the thermostat housing. Over time, this can lead to extensive damage to the components and electrical components inside the unit. High-quality seals are designed to last for many years even in harsh conditions and can be used in a wide range of environments. The proper choice of seal depends on the particular application and the operating environment where the seal will be used. https://www.totalperformance.net.au/LS-Water-Pump-Mounting-Gasket-Set-O-ring-thermostat-seal-LS1-LS2-LS3-HOLDEN-COMMODORE-12630223