These containers are designed to carry cargo that has to be handled with cranes and cannot be loaded through side panels or front doors. They can also be used for the movement of specific kinds of over-dimensional cargo. The defining feature of these containers is their convertible top, which can be removed to allow for the loading of cargo from above. This feature is particularly useful for tall items that exceed the height limitations of standard containers. They come in standard lengths of 20 feet and 40 feet, similar to conventional shipping containers, but the open top provides greater flexibility in accommodating taller cargo.