Island range hoods are generally made for ducted installation, which means that they push the air up through an existent vent in your home. If you don't have a vent, it may be possible to add one in order to be able to install a hood, but this generally depends on the layout of your house. Ductless hoods can be installed anywhere in the kitchen, without the need of a vent nearby. Some models, such as the AKDY Island Mount Range Hood, for example, can be installed in a ductless mode, but you need to purchase parts separately in order to be able to do that.