This is the horn bushing that is on the worm shaft where the horn brush makes contact. The bushing is insulated so it doesn't make a ground on the worm shaft.
Note: On original and reproduction columns reaming out the plastic part of the bushing may be required. If you don't have access to a reamer and it is close to fitting use sand paper if it is not close use a dremel tool with light sand paper. We usually use lock tight to bond it to the tube.
1 Required per Jeep.