There are also several sizes and weight categories of tow truck. The lightest models are usually based on light truck and van chassis offering boom and tow weights of around , making them ideal for car towing. Most flatbed-type vehicles are based on medium duty and heavy duty trucks to provide the chassis strength necessary to carry entire vehicles. A step up from that are medium-duty tow trucks offering boom capacity of . Heavier still are the heavy duty tow trucks based on chassis used by semi trucks, with multiple axles and the ability to tow fully loaded semi truck and trailer combinations, with boom capacity from . At the top are the rotators, which can range from (though lighter models do exist as seen at the right) and often come with a wealth of other features per customer specification.