Idle, fuel pump loop or pump saver check valve -6. This valve allows the unused fuel at an idle to return to the tank, trim a fuel pump that is to big, or save the pump when you slam the butterflies shut after a pass down the drag strip and can be set to your specifications.
The check valve body is made from alum. and weights almost nothing so if you trying to save weight on your car here is your chance. Anodized for corrosion protection.
Please specify spring pressure when ordering and if you are not sure let RBS help you.