Product review (5 stars): Excellent Roof Vent cap
I ordered this a couple of these vents for my roof several years ago (for the bathroom vents).  They fit perfectly and replaced the pathetic vents the builder installed.  Had my roof replaced and ordered replacements so the new roof would have new vents.  Exactly what I wanted.  Did have the contractor paint them white to match the roof since they don't sell any white ones - look great and work perfectly.  If I ever need a new roof these will be on it.

The one flaw is that if you don't buy the "whole" kit you will have to buy the duct collars as a separate item - the vent is useless without the collars, so Broan-NuTone should include the 4" collars too.  Oh, and be sure you wear heavy gloves when you screw the collars on the vent cap as the sheet metal can really do some damage if you are not very careful & screw them on before you install the cap - it's much easier to get the collar on the cap before hand so you don't have to do it in the attic - don't ask me how I know.