Dumbwaiters are small elevators which are not intended for carrying people. Instead they are specially constructed to carry objects such as food, merchandise and other products. They can be found in restaurants, commercial and private buildings and private homes normally for use between two floors. They are generally based in the kitchen of the building to place prepared food to be served to the upper or lower floors depending on the building. It typically consists of a movable frame in a shaft which is operated by a pulley or electric motor. They are normally self closing and contain features such as fireproof doors and locks preventing them from being opened unless they have stopped at the required level. More recent dumbwaiters can be more sophisticated using special electric motors and automated systems with specialised containers. Recently constructed dumbwaiters in libraries and office towers are much larger than those used in restaurants and are capable of carrying loads of up to 1000 pounds.