Inexpensive, easy to install. Stays in place on own for now, but I can see the need for screws through the flange if it is has to be removed and re-installed for painting the soffits. Fortunately, the flange is plenty large to accomodate this. The flex duct holds secure with use of a zip tie (not included but required by code in a few municipalities). This is a case of simple is better in my opinion and our fans work many times better than they did when ducts were routed up and looped around a rafter brace by the original builder.
Easy to Install,