Though aircraft have long been an important element in the lives of most Americans, insurance of aircraft exposures has remained outside the mainstream of property and liability insurance markets. Aircraft hull and liability insurance is the counterpart of personal or commercial auto policies coverage. Aircraft products insurance is the counterpart of products liability cover. Air cargo insurance is mirrored in motor truck cargo. Hangarkeepers liability is akin to garagekeepers coverage. As with any specialty line of insurance, the absence of standardized forms limits practice to specialists in the line.