Trailer Valet XL Trailer Dolly Now with "Never Flat" solid rubber tires. Included drill attachment allows you to use most battery powered and corded drills and turns your Trailer Valet XL into a motorized dolly. Automatic brake keeps trailer from rolling. Rugged steel construction with black powder coat and zinc-nickel plating resists rust and 300-Hour salt spray rating. 10,000lb weight capacity on a flat packed surfaces such as concrete and asphalt. If considering a sloped surface above 2 degrees contact manufacture for more info.