Product review (5 stars): Fits the bill
Purchased an existing house, and the dryer vent was just above the ground...  found evidence of visitors (they were helped by the build-up of lint, which prevented the flap from closing).  Removed the old vent cap, replaced with this one...  raises the exhaust up several inches, and - no more visitors...  Needed a bit of silicon calk, but small price to pay...