The Edelbrock Square-Bore Heat Insulator Gasket is designed to prevent fuel percolation in Performer Series and Thunder Series AVS carburetors exposed to extreme underhood temperatures. This square-bore heat insulator gasket is used for Edelbrock dual-quad manifolds. This is a 4-barrel gasket, which is made up of a nitrile rubber composite. It has a 2-hole divided center and is 0. 125 inch thickness. This gasket comes with extended carburetor studs.