A stacker is also known as a reach stacker. These look like forklifts but have a difference in how they function. A forklift and reach stacker can ascend or descend their folks, but a reach stacker can also extend and retract heir forks. This is what gives them an edge when there is a need to stack containers for storage or transport. They can stack rows and rows very quickly and stack them higher than other equipment (except for a crane).
You will see a reach handler at any port but are used most by small to mid-size ports where a crane is unnecessary. Many fishermen use them at ports to make unloading their seafood far easier. They will use cranes depending on the type of seafood they caught. Others will use special containers that are not as large as cargo containers but are still heavy to lift.
There is also a specialized version of the reach stacker for the military. They are designed for rough terrain and can hold more than many reach stackers on the market, upwards of 50,000 pounds! The rough terrain can include rocky areas, beaches, and even sea water. These become incredibly helpful when the military is working to assist in cleanup of decimated areas or to clear a demolition job. They can also transport many necessary supplies and materials with ease with a rough terrain reach stacker.