Dress up your engine in your 6.6L Duramax with the Sinister Diesel Coolant Reservoir cap. Featuring an anodized gray finish and built from billet aluminum, you can count only great looks and a product that won't crack like the factory cap for years to come.
This cap is is made from CNC machined, solid billet T6-6061 aluminum with an interior pressure relief system, so it will continue to function even in case of a gasket failure.