These liners are made to be mounted inside a decorative hood that you create out of wood, plaster, metal or tile. The BHSLD wall hood liner gives you all the power of a Vent-A-Hood wall hood. The only place where the liner and the outside cover must meet is at the bottom edge of the metal liner in both width and depth. These hood liners feature Vent-A-Hood's Magic Lung filter-less design, which allows you to get more out of the blower. The Magic Lung blower performs better because it uses centrifugal filtration instead of mesh or baffle filtration. Operation is the quietest in the industry, so turning on your hood won't put an end to conversation. The dual level halogen lighting illuminates the cooktop. The SensaSource automatically adjusts the blower speed as heat increases. There are many other reasons to buy a hood liner: they are pre-wired, pre-assembled, and far less expensive than custom made liners.