A casing assembly adapted for a carrier and comprising a casing adapted to be stacked on the carrier and a latch mechanism comprising a first component, a second component, and a third component. The first component and the second component are movable by each other and are rotatably disposed on the casing, the third component is slidably disposed on the casing and movable by the second component, such that the third component is releasably engaged with a first engaging component of the carrier as the first component moves the second component.