Kawasaki Strong As the newest edition to the MULEâ„¢ family, the MULE PRO-FXâ„¢ is our fastest, most powerful, three-passenger MULE side x side ever. Built on the same rugged platform as the PRO-FXTâ„¢, this revolutionary side x side also comes equipped with the largest cargo bed in its class. To top it off, the PRO-FX is backed by the Kawasaki Strong 3-Year Limited Warranty.