Bart - they have so much stuff you have to keep refining your search; but if you are patient and go through fasteners, nuts, hex nuts, hex jam nuts, and then scroll down on the left column, you will find finishes at the very bottom. Black oxide is listed.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop