These steering wheel adaptors are made to adapt the 9-bolt patterns of a steering wheel to the tapered, splined top shaft of a steering column. All ididit adaptors will fit most ididit columns as well as most 1969 or newer GM passenger car columns and are secured in place with a single nut. A horn wire is included. These adaptors will match aftermarket wheels from Lecarra, Billet Specialties, Budnik, Colorado Custom, and more! Standard size is 2.5″ deep.