You need to buy the exhaust / Range hood plus the Recirculating kit. We were not advised at time of purchase however AOL resolved the issue. The kit is to recirculate or vent outside depending on the requirement of the customer. It works better than any other unit I have had, always best to vent outside however almost as good and perfect for an apartment. As a chef I create a lot of smoke so it suits my needs perfectly given that I can not vent outside.