This blockoff plate allows you to remove the J-Tube section of the fuel-return system, located under the intake manifold, bolted to the block. When you install an external AFPR, you will bypass the J-Tube which incorporates a pinhole orafice as the factory backup fuel pressure regulation. You can't simply remove the J-Tube and it's mounting plate because there is a hole in the block behind the plate. This blockoff lets you perform the final cosmetic finish on your fuel project. This plate is produced by a member of the SOGI community in the USA. This would cover the port where part #23809 bolts-on in the illustration

The J-Tube blockoff plate is made out of Stainless Steel and comes with a gasket.