CB Antenna stud mount. Heavy duty construction. Designed to fit nearly any mobile CB antenna. Comes with a SO-239 connector at the base for connecting a PL259 coax connector. Top is 3/8 in with 24 threads to accommodate standard CB antennas like a Firestik, Francis, or Wilson. Requires 1/2 inch hole. Common stud mount installation issues are the wrong order of the washers, make sure to pay attention to the installation instructions. Stud Nut > Flat Washer > Lock Washer > | BRACKET | > Bottom of Stud.