LARSEN~Stud/NMOHF Mnt GPS Ant Combined high performance GPS antenna with the an NMO high frequency mount on the top for easy combination with virtually any NMO mount antenna from 27 MHz to 6.0 GHz. Simply pull the center pin and insulator to convert from low frequency to high frequency applications. Pulling the center pin creates a coax-type connection optimal for high frequency applications. The larger center contact pin provides additional strength against downward compression during low frequency installations, resulting in better Low Frequency VSWR.