A:Answer Hi there, thank you for reaching out with this question. This allows for some microwave installations in deep cabinets to fit better over your range. Without it, many microwave models will not be able to vent properly. As always, we recommend checking the installation instructions for your model to make sure all requirements can be met. We hope this helps, and please be sure to let us know if there are any ways we can assist you in the future. -Elliot@GEA
