When one buys a ramp or ramps with a fixed length, is usability is governed totally by the height and size of the steps. If it is of a height of 6 feet, it can be used for only one application. When it is taken outside on a holiday or somewhere else, one might find that they actually need a longer one, maybe of 8 feet. So it is better purchasing the ones that can be lengthened by simply purchasing a few spare treads, which can be conveniently left in the car itself. Heavy equipment can be moved very easily along them.