Tumble dryers are often integrated with a Washing machine, in the form of laundry centers and washer-dryer combos, which stacks the dryer on top of the washer and integrates the controls for both machines in a single control panel, or in the form of "washer-dryer combos" which are essentially a front loading washing machine with an integrated dryer. Often the washer and dryer functions will have a different capacity, with the dryer usually having a lower capacity than the washer. Tumble dryers can also be top loading, in which the drum is loaded from the top of the machine and the drum's ends are in the left and right sides, instead of the more conventional front and rear. They can be as thin as 40 cm in width, and may include detachable racks for drying items like plush toys and footwear.