These are high quality gaskets that works well on those hard to seal applications. The low density fiber & rubber blend gasket material seals those minor head imperfections with a low clamp force. At .187 inch, the extra thickness can also offer slightly more clearance for roller rockers. Ideal for all those high performance applications where you take the valve covers off and on a lot, and sticking is a problem.brbrFits all 1965-2000 Chevy Big Blocks: 366,396,402,427,454 including GM (General Motors) Gen VI Crate Engines like the 502 and 572.

Product Features:

• Manufactured from high-density cork/rubber blend gasket material
• A black latex rubber coating is applied to the outside of gasket to help seal minor flange irregularities and eliminate the possibility of oil leakage
• Creates a positive seal by controlled swelling of the gasket material when exposed to hot engine oil.
• For OE replacement, high performance street, drag race and oval track use.
• .187" thick for additonal valve train clearance
• Handles Ex Flange Pressure
• Forms Leak Proof Seal
• Black Latex Coating