Off-frame modular dwellings differ from mobile homes largely in part because of their lack of axles or frame typical of mobile homes, meaning that they are typically transported to building sites by means of flat-bed trucks. However, some modular dwellings are built on steel frames (on-frame modulars), which can be used for transportation to building sites. Many modular homes are of multi-level design, and are often set in place using a crane. [Citation: http://en.wikipedia.org/wiki/Modular_home]