The types of business aircraft vary widely, ranging from propeller-driven aircraft to jets to helicopters. The fleet includes everything from piston aircraft not much bigger than a car and capable of flying just a few hundred miles before re-fueling, to jets that seat more than a dozen people and are capable of making non-stop international flights. However, the vast majority of business aircraft seat six passengers in a cabin roughly the size of a large SUV and fly an average stage length of less than 1,000 miles. Depending on their capability, these aircraft may fly at altitudes below the airlines (below 20,000 feet) or above the airlines (above 40,000 feet).