Install a Fulton F2 jack onto your trailer's existing Fulton XP10 or XP15 jack mount. Simply bolt this adapter plate onto your welded-on mount. Sharkskin finish resists corrosion. 1/2" Pull pin hole.Sharkskin Coating for Corrosion Resistance This plate is coated with Fulton's Sharkskin finish to resist corrosion, making it ideal for your boat or snowmobile trailer. Sharkskin products undergo a test in which they are sprayed with a 5-percent salt solution to determine corrosion resistance over time.