The Chris King fork cone, baseplate for the NoThreadSet 1 1/8-inch headset.
There is nothing more frustrating than when, whilst changing the fork, the headset cone can only be removed with considerable force. Afterwards, it is often bent out of shape.
Herstellerinformation: Manufacturer details: Chris King, 2801 NW Nela St, 97210 Portland, Oregon, United States, http://chrisking.com