Dual-inlet Holley ® 4-bbl Carburetors w/ 3/8" Hose & 9-5/16" spacing. 4150 (pri. & sec. metering blocks) Hex design allows wrenching area for easier installation of fittings. Chrome plated steel tubing, brass fittings and silver brazed connections. Mandrel bent 3/8" tubing 5/16˝-18 outlet threads Includes 7/8-20 bowl adapters