This set includes 2 pieces of dust cap cup grease covers for trailer wheel hub bearing axle. The covers have an outer diameter of 2.557 inches and are made of durable metal with a silver tone shell color. The manufacturer part number is 121T and it is compatible with Carry On Trailer brand. These dust cap cup grease covers are essential for protecting your trailer's wheel hub bearing axle from dust, dirt, and moisture. They are easy to install and will ensure that your trailer's wheels are always in top condition. Get this reliable product now and enjoy worry-free travels on the road.