Fulton 500320 XP Adapter Kit for F2 Swivel Mount with 4" Frame Fulton F2 Jack Adapter Plate allows you to upgrade from a Fulton Center-Bolt Swivel Mount Jack to an F2 Series Marine and Recreational Jack Fits Fulton's patented center-bolt design - used on XP10 and XP15 weld-on jacks Heavy-duty, cast aluminum mount is tapered, moving wheel closer to center line of trailer frame to optimize castering performance; installs easily - no drilling or welding required All necessary mounting hardware and complete installation instructions included Backed by Fulton's 5 Year Limited Warranty