Compatibility:Compatible with Holley Carb Chevy 4BBL SBC BBC 0.5.Compatible with Holley 4150/4160.
Ported Design Spacers:Ported Design;
Package list:Package Includes mounting hardware and gaskets.
Thickness: 0.5",1/2
Phenolic material:Phenolic material is a type of plastic resin which has excellent insulating properties,Made of phenolic resin and engineered to reduce heat transfer from the intake manifold to the carburetor that provides a denser air/fuel mixutre for increased power and efficiency.