This mini magnetic antenna is the one that comes with the Drive 4G-X. If you are looking to replace or get an extra one, this is the one to get. Many RVers will get an extra antenna so that if they move the booster to a different vehicle, like from a truck to a 5th wheel RV, then you don't have to move everything.
Multi-Band Mini Magnet Mount Antenna. 4.18-inch Vehicle Antenna For Mobile Cell Phone Signal Boosters with 12.5-feet of RG-174 Cable and SMA-Male Connector. 50 Ohm, 301126 Mobile Omni-Antenna Receives Signals from All Directions.