Product review (4 stars): Excellent Vent - No Instructions, Poor Product Packaging, Damaged prior to shipment
The vent has a good feature not listed in the description - a magnetic latch that holds the outer cover closed securely.
There are no instructions included, but you can find them on the NoPestVent dot com website.  The site is also helpful in determining which of the three vent types is best suited to your application. For example this "low profile" vent is narrower than the typical square-shaped vent.  This dimension combined with the beveled corners may leave exposed something your old vent used to hide. They have another style available if you need to hide a larger area.
  I would rate this five stars if it were supplied with instructions and if it were packaged in a way that did not damage the duct tube.  It comes with the vent tube folded nearly flat around the vent, then wrapped tight with some sort of adhesive backed bubble wrap that is very difficult to remove.  The wrapping process caused a crease in the duct tube that had to be worked out before it could be formed into a tube.  Also, the end of the tube was dented and required considerable reshaping before it would fit into the vent.  This damage did not occur during shipment, as there was no damage to the shipping package.