Large containers generally refer to 40-foot containers, usually 40GP and 40HQ. 45-foot containers are generally regarded as special containers. A small container generally refers to a 20-foot container, usually 20GP. Double-back refers to two 20-foot small cabinets. For instance, a trailer is pulling two 20-foot small cabinets at the same time; When hoisting at the port, two 20-foot containers were hoisted onto the ship at one time.
