Firestik K-11 Magnet Mount w/18' Coax CB RADIO ANTENNA MAGNET MOUNT Magnet mount has a 4.9 (125mm) base Comes with 18 ft of Fire-Flex coax Accept 3/8" x 24 thread antennas up to 3 ft To protect the vehicle finish, an adhesive backed mylar disk is affixed to the bottom of the mount