In our goal of being your best source for all things towing, the CURT line of trailer jacks is designed with care and manufactured with pride. CURT jacks are made with quality to promote the life and function of your trailer, and they come in several different styles to accommodate your needs, whether you are a frequenter of the boat landing, the campground, the racetrack or the farm. This replacement cap is intended to fit a CURT marine jack to keep water and grime out of the internal mechanisms. It is constructed from plastic and comes with a set screw.