When the stock head gaskets in your truck are blown or leaky, a Sinister Diesel Duramax head gasket is the perfect way to get everything running normal again. You'll find these steel head gaskets are a huge upgrade, having been designed specifically for the harsh conditions of a turbo diesel engine. Use this head gasket on any LB7, LLY, LBZ, and LMM 2001 - 2010 Duramax engine., The tough construction of these Sinister Diesel head gaskets includes 5 layers of stainless steel sandwiched, creating an heavy - duty seal for each cylinder, despite extreme compression and heat. Each gasket is also coated with fluoroelastomer (FKM) to prevent the flow of fluids past the gasket, ensuring a secure seal between the cylinder head and block. Features Construction - Multi - layer Steel, Product Design - Driver Side, Grade A .95mm thick, Coated with Adaptive fluoroelastomer (FKM), Kit Includes - (1) Sinister Diesel Black Diamond 20mm Head Gasket