This is the open center version of the heat insulator, meant for single-plane manifolds where the plenum is already common beneath the carburetor. Its job is thermal: putting a break between a hot manifold and the float bowls, which is what prevents fuel percolation and the hard hot restart that comes with it.

Edelbrock 9265 Heat Insulator Details:

• 0.320 in. thick nitrile rubber composite insulator.
• Square bore shape with an open center for single-plane manifolds.
• For four-barrel carburetors.
• Reduces heat transfer from the manifold into the carburetor body.
• Sold individually. Use the divided center version 9266 on dual-plane manifolds instead.