Mr. Carb Base Vibration Isolator -Square Flange 4-Barrel,Open Center Vibration Isolating Base Mr Gasket1 4 inch thick closed cell foam rubber material is designed to act as a shock absorber to dampen fuel vibration, reduce fuel foaming and cut down on erratic needle seat motion all to stabilize the fuel curve. 1 4? thick closed cell foam rubber material Designed to stabilize fuel curve in carburetor fuel bowls Acts as a shock absorber to dampen fuel vibration, reduce fuel foaming and cut down Details: Emission Code: 5 Material: closed cell foam rubber