You are bidding on a used 1970s vintage Holley list number 6210 650 cfm mechanical secondary spread bore four barrel carburetor with dual accelerator pumps.   It was intended to be a bolt on replacement for Rochester Quadrajet equipped Chevrolet V8 engines.   The carb is complete, and the throttle plates, adjustment screws, and other linkages move freely.   As can be seen from the pictures, it's clean inside where it really counts.   As with any used Holley carburetor, all of the gaskets should be replaced before use.   Happy bidding!