Spectre's polished cast aluminum low profile plenum has a 4 inch inlet. It is 2.4 inches tall between the carburetor and the bottom of the hood which makes it great for low clearance applications. It measures 9.25 inches from the air cleaner stud to the inlet and 7.25 inches across the plenum at the air cleaner stud. This plenum fits carburetors and TBI throttle bodies with a 5-1/8 inch inlet. The 4 inch single inlet is designed to match up to all Spectre 4 inch tubing, filters and accessories. Use with Spectre 4208 air cleaner nut (sold seperately).