Early (vintage - classic) late 60's, early 70's) GM air cleaner breather. This has the slightly larger diameter (flow) relative to the small block air cleaners and also has the larger inlet snorkel. This fits rochester quadrajet carburetors but may also fit other carbs including edelbrock, etc. These would have been used on the bigger GM (4 bbl) engines at that time, ie: 400, 428, 454, 427, 396, 455, etc. This is in very good, clean condition and ready to go.