Choosing a venting system for your range depends on a variety of factors including the width of the cooking surface (or width of your range), how powerful the range is (which determines what type of fan speed you need - rated in CFMs, cubic feet per minute,), how long the duct work has to travel to reach the outside, and last (but not least) what type of style you want to look at. It's very important that when you're selecting a hood that you have strong communication between your team of contractors and your appliance retailer so that all `i's` are dotted and `t's` are crossed.