Stainless Steel Super heavy duty antenna stud. 3/8-24 , So-239 input for cable. Made with superior materials and is best mounted to a strong surface. Perfect to use as a mirror mount or bumper mount and can withstand virtually any antenna you have that is threaded as 3/8-24, and works great with a 102" whip  This stud will fit a 3/8" hole. The plastic washer/insulator is oversized to help spread out weight, but protruding portion of it that is supposed to stick into the hole in your mount is still 3/8", so you don't have to buy any special brackets or drill a larger hole for this to fit.  PREMIUM CB antenna mount that once installed will probably outlive the vehicle it's installed on.